A Voyage of Discovery and Research in the Southern and Antarctic Regions
DISCOVERY AND RESEARCH
SOUTHERN AND ANTARCTIC REGIONS,
DURING THE YEARS 1839–43.
CAPTAIN SIR JAMES CLARK ROSS, R.N.
KNT., D.C.L. OXON., F.R.S., ETC.
WITH PLATES, MAPS, AND WOODCUTS.
IN TWO VOLUMES.
JOHN MURRAY, ALBEMARLE STREET.
Spottiswoode and Shaw,
THE RIGHT HONOURABLE
THE EARL OF MINTO, G.C.B.
LORD PRIVY SEAL,
LATE FIRST LORD COMMISSIONER OF THE ADMIRALTY,
UNDER WHOSE AUSPICES
THE EXPEDITION OF SCIENTIFIC RESEARCH TO THE ANTARCTIC REGIONS
WAS SENT FORTH,
THIS NARRATIVE OF ITS PROCEEDINGS
WITH GRATITUDE AND RESPECT,
BY HIS LORDSHIP'S OBEDIENT AND FAITHFUL SERVANT,
JAMES CLARK ROSS.
Aston House, Aylesbury,
1st June, 1847.
At the eighth meeting of the British Association for the Advancement of Science, held at Newcastle, in August, 1838, the attention of the physical section of that body was directed to the number and importance of desiderata in that great practical branch of science called Terrestrial Magnetism, by Lieutenant-Colonel Sabine of the Royal Artillery; and a Committee was appointed, consisting of Sir John Herschel, Mr. Whewell (now Master of Trinity College, Cambridge), Mr. Peacock (now Dean of Ely), and Professor Lloyd, of Trinity College, Dublin, to represent to Her Majesty's Government a series of resolutions adopted by the British Association; and as these resolutions exhibit the general outline of objects sought to be attained, they are inserted here, as pointing out clearly the causes in which the Expedition to the Antarctic regions originated.
"Resolved—1. That the British Association views with high interest the system of simultaneous magnetic observations which has been for some time carried on in Germany and various parts of Europe, and the important results to which it has already led; and that they consider it highly desirable that similar series of observations, regularly continued in correspondence with, and in extension of these, should be instituted in various parts of the British dominions.
"2. That this Association considers the following localities as particularly important:—Canada, Ceylon, St. Helena, Van Diemen's Land, and Mauritius, or the Cape of Good Hope; and that they are willing to supply instruments for their use.
"3. That in these series of observations the three elements of horizontal direction, dip, and intensity, or their theoretical equivalents, be insisted on, as also their hourly changes, and, on appointed days, their momentary fluctuations.
"4. That the Association considers it highly important that the deficiency, yet existing in our knowledge of terrestrial magnetism in the southern hemisphere, should be supplied by observations of the magnetic direction and intensity, especially in the high southern latitudes between the meridians of New Holland and Cape Horn; and they desire strongly to recommend to Her Majesty's government the appointment of a naval expedition expressly directed to that object.
"5. That in the event of such expedition being undertaken, it would be desirable that the officers charged with its conduct should prosecute both branches of the observation alluded to in Resolution 3., so far as circumstances will permit.
"6. That it would be most desirable that the observations so performed, both at the fixed stations and in the course of the expedition, should be communicated to Professor Lloyd.
"7. That Sir J. Herschel, Mr. Whewell, Mr. Peacock, and Professor Lloyd, be appointed a Committee to represent to Government these recommendations."
A memorial was addressed to the Government by the Committee above named, embodying the chief arguments for taking up the cause as a national concern, and specifying more particularly the objects proposed to be accomplished, and the means of their accomplishment. This memorial, on its presentation to Lord Melbourne, was not only supported by the personal arguments of the eminent philosophers by whom it was framed, but on its being referred by the Government to the President and Council of the Royal Society, (its acknowledged advisers upon all points of scientific inquiry,) by similar and even more urgent representations on their part, "who, on this occasion, in a manner most honourable to themselves, and casting behind them every feeling but an earnest desire to render available to science the ancient and established credit of their institution, threw themselves unreservedly and with their whole weight into the scale, with immediate and decisive effect." The strong interest taken in the cause by their President, the Marquis of Northampton, on all occasions a warm and zealous friend to science, contributed, without doubt, not a little to this result.
The following Report of a joint committee of physics and meteorology, adopted by the Council of the Royal Society, on the propriety of recommending the establishment of fixed magnetic observatories, and the equipment of a naval expedition for magnetic observations in the antarctic seas, to Her Majesty's Government, was presented to Lord Melbourne by the deputation named in the appended resolutions of the Council:—
"The subject of terrestrial magnetism has recently received some very important accessions which have materially affected not only the point of view in which henceforward it will be theoretically contemplated, but also the modes of observation which will require to be adopted for completing our knowledge of the actual state of the magnetic phenomena, and furnishing accurate data for the construction and verification of theoretical systems. It was for a long time supposed that the changes in the position assumed by the needle at any particular point on the earth's surface, might be conceived as resulting from regular laws of periodicity, having for their arguments, first, a great magnetic cycle of several centuries, depending on unknown, and perhaps internal movements or relations; and, secondly, on the periodic alternations of heat and cold, depending on the annual and diurnal movements of the sun. The discovery of the affection of the needle by the aurora borealis, and of the existence of minute and irregular movements, which might be referred either to unperceived auroras or to other local and temporary causes, sufficed to show that the laws of terrestrial magnetism are not so simple as to admit of this summary form of expression; and the important discovery, first announced, we believe, by Baron von Humboldt, that those temporary changes take place simultaneously at great distances in point of locality, (a discovery which has since been remarkably confirmed and extended to very great intervals of distance, so as to include the whole extent of the European continent, by Gauss and Weber, and their coadjutors of the German Magnetic Association,) has sufficed to show that the gist of the inquiry lies deeper, and depends upon relations far more complex, while at the same time the dominion of what might previously have been regarded as local agency, would require, in the new views consequent on the establishment of these facts, to be extended far beyond what ordinary usage would authorise as a just application of that epithet.
"For a long time in the history of terrestrial magnetism the variation alone was attended to. The consideration of the dip was then superadded; but the observation of this element being more difficult and delicate, our knowledge of the actual and past state of the dip over the earth's surface is lamentably deficient. It has lately appeared, however, that this element can be observed with considerable approximation, though not with nicety, at sea, so that no reason subsists why materials for a chart of the dip, analogous to that of variation, should not be systematically collected. Lastly, the intensity has come to be added to the list of observanda; and from the great facility and exactness with which it can be determined, this branch of magnetic knowledge has in fact made most rapid progress.
"These three elements, the horizontal direction, the dip, and the intensity, require to be precisely ascertained before the magnetic state of any given station on the globe can be said to be fully determined. Nor can either of them, theoretically speaking, be said to be more important than the others, though the direction, on account of its immediate use to navigators, has hitherto had the greatest stress laid upon it, and been reduced into elaborate charts. A chart of the lines of total intensity has been recently constructed by Major Sabine.
"All these elements are, at each point, now ascertained to be in a constant state of fluctuation, and affected by those transient and irregular changes which are above alluded to; and the investigation of the laws, extent, and mutual relations of these changes, is now become essential to the successful prosecution of magnetic discovery, for the following reasons:—
"1st. That the progressive and periodical being mixed up with the transitory changes, it is impossible to separate them so as to obtain a correct knowledge and analysis of the former without taking express account of and eliminating the latter, any more than it would be practicable to obtain measures of the sea-level available for an inquiry into the tides, without destroying the irregular fluctuation produced by waves.
"2ndly. That the secular magnetic changes cannot be concluded from comparatively short series of observation, without giving to those observations extreme nicety, so as to determine with perfect precision the mean state of the elements at the two extremes of the period embraced, which, as already observed, presupposes a knowledge of the casual deviations.
"3rdly. It seems very probable that discordances found to exist between results obtained by different observers, or by the same at different times, may be, in fact, not owing to error of observation, but may be due to the influence of these transitory fluctuations in the elements themselves.
"4thly and lastly, Because the theory of these transitory changes is in itself one of the most interesting and important points to which the attention of magnetic inquirers can be turned, as they are no doubt intimately connected with the general causes of terrestrial magnetism, and will probably lead us to a much more perfect knowledge of those causes than we now possess.
"Actuated by these impressions, on the occasion of a letter addressed by Baron von Humboldt to His Royal Highness the Duke of Sussex, P.R.S., the Council of this Society, on April 13. 1837, resolved to apply to Government for aid in prosecuting, in conjunction with the German Magnetic Association, a series of simultaneous observations; and in consequence of an application founded on such their resolution, a grant of money was obtained for the purchase of instruments for that purpose. By reason, however, of the details and manipulations of the methods then recently introduced into magnetic observations by Gauss being at that time neither completely perfected, nor their superiority over the old methods fully established by general practice, the precise apparatus to be employed in these operations was not at the time agreed upon, and was still under discussion, subject to the report of the Astronomer Royal on the performance of an instrument on Gauss's principle established at Greenwich, at the time when the subject in its present more extended form was referred by the Council to this Joint Committee, so that the grant in question has not, in point of fact, been employed or called for. The Committee consider this as in some respects fortunate, as in consequence of the delay time has been given for a much maturer consideration of the whole subject; and should it now be taken up as a matter of public concern, they consider that it will be necessary to provide for a more continuous and systematic series of observations, by observers regularly appointed for the purpose and provided with instruments and means considerably more costly than those contemplated on the occasion in question.
"On the general advisableness of calling for public assistance in the prosecution of the extensive subject of terrestrial magnetism, in both the modes referred to them for their consideration, (viz. by magnetic observatories established at several stations properly selected on land, and by a naval expedition expressly directed to such observations in the antarctic seas,) your Committee are fully agreed. They consider the subject to have now attained a degree of theoretical as well as of practical importance, and to afford a scope for the application of exact inquiry which it has never before enjoyed, and which are such as fully to justify its recommendation by the Royal Society to a revival of that national support to which we are indebted for the first chart of variations constructed by our illustrious countryman Halley in A.D. 1701, on the basis of observations collected in a voyage of discovery expressly equipped for that purpose by the British government.
"As regards the first branch of the question referred to their consideration, they are of opinion that the stations which have been suggested to them, viz. Canada, St. Helena, the Cape, Van Diemen's Land, and Ceylon (or Madras), are well selected, and perhaps as numerous as they could venture to recommend, considering the expense which would require to be incurred at each, and, that in each of these stations it would be desirable,
1st. That regular hourly observations should be made (at least during the daytime) of the fluctuations of the three elements of variation, dip, and intensity, or their equivalents, with magnetometers on the more improved construction, during a period of three years from their commencement.
"2ndly. That on days, and on a plan appointed, agreed on in concert with one another and with European observatories, the fluctuations of the same elements should be observed during twenty-four successive hours, strictly simultaneous with one another, and at intervals of not more than five minutes.
"3rdly. That the absolute values of the same elements shall be determined at each station, in reference to the fluctuating values above mentioned, with all possible care and precision, at several epochs comprehended within the period allowed.
"4thly. That in the event of a naval expedition of magnetic discovery being despatched, observations be also instituted at each fixed station, in correspondence with, and on a plan concerted with the commander of, such expedition.
"As regards the second branch of the subject referred to them, viz., the proposal of an antarctic voyage of magnetic research, they are of opinion, as already generally expressed, that such a voyage would be, in the present state of the subject, productive of results of the highest importance and value; and they ground this opinion on the following reasons:—
"1st. That great and notorious deficiencies exist in our knowledge of the course of the variation lines generally, but especially in the antarctic seas, and that the true position of the southern magnetic pole or poles can scarcely even be conjectured with any probability from the data already known.
"2ndly. That our knowledge of the dip throughout those regions, and the whole southern hemisphere, is even yet more defective, and that even such observations of this element as could be procured at sea, still more by landing on ice, &c., would have especial value.
"3rdly. That the intensity lines in those regions rest on observations far too few to justify any sure reliance on their courses over a large part of their extent, and over the rest are altogether conjectural. Nevertheless, that there is good reason to believe in the existence and accessibility of two points of maximum intensity in the southern as in the northern hemisphere, the attainment of which would be highly interesting and important.
4thly. That a correct knowledge of the courses of these lines, especially where they approach their respective poles, is to be regarded as a first and, indeed, indispensable preliminary step to the construction of a rigorous and complete theory of terrestrial magnetism.
"5thly. That during the progress of such an expedition, opportunities would of necessity occur (and should be expressly sought) to observe the transitory fluctuations of the magnetic elements in simultaneous conjunction with observations at the fixed stations and in Europe, and so to furnish data for the investigation of these changes in localities very unlikely to be revisited for any purposes, except those connected with scientific inquiries.
"Your Committee, in making this Report, think it unnecessary to go into any minute details relative to the instruments or other matériel required for the proposed operations, still less into those of the conduct of the operations themselves. Should such be required from them, it will then be time to enter further into these and other points, when the Committee will most readily devote themselves to the fullest consideration of the subject.
"J. F. W. Herschel,
"Chairman of the Joint Physical and
RESOLUTIONS OF THE COUNCIL.
1. That this Report be received and approved.
2. That the Council, deeply impressed with the importance of the scientific objects which might be attained by an antarctic expedition, particularly by the institution of magnetic observations in southern regions, do earnestly recommend that Her Majesty's Government be pleased to direct the equipment of such an expedition.
3. That the imperfect state of our present knowledge of the amount and fluctuations of the magnetic elements, renders the establishment of fixed magnetical observatories, for a limited time, at various points of the earth's surface, highly desirable, particularly in Canada, St. Helena, Van Diemen's Land and Ceylon, and at the Cape of Good Hope; and that the Council do earnestly recommend Her Majesty's Government to cause such observatories to be established.
4. That a deputation, consisting of the President, Treasurer, and Secretaries of the Society, Sir John F. W. Herschel, the Chairman, and Major Sabine and Mr. Wheatstone, the Secretaries of the joint Committee of Physics and Meteorology, be requested to communicate the above Resolutions to Lord Melbourne, and to urge on the Government the adoption of the measures therein proposed.
Thus urged upon the Government by the most illustrious philosophers of our country, the request was acceded to by Lord Melbourne; and the Lords Commissioners of the Admiralty being pleased to honour me with the command, I received my commission for Her Majesty's ship Erebus, on the 8th of April, 1839, and their Lordships' directions to proceed with the equipment of the expedition upon the most liberal scale, to be provided with all requisite means to carry into full execution the several points suggested, and observations recommended, by the two learned bodies, in the most complete manner. The Erebus, a bomb of three hundred and seventy tons, like all others of her class, was of strong build and with a capacious hold. The second vessel appointed for the service was the Terror, of three hundred and forty tons; she had been originally strengthened for contending with the ice of the arctic seas, upon the occasion of the detention of so many of our whale ships in Baffin's Bay, during the winter of 1836, and employed in the subsequent summer under the command of Sir George Back, upon his arduous but unsuccessful attempt to reach Repulse Bay. The damages she sustained during that voyage had already been repaired, and her fortification being considered perfectly sufficient, she was not commissioned until a month later, by my trusty and tried friend and messmate, Commander Francis Rawdon Moira Crozier; and from the numerous applicants for the service, the following officers were selected and appointed to the Erebus and Terror:—
|Captain.||James Clark Ross.||Commander.||Francis R. M. Crozier.|
|Lieutenant.||Edward Joseph Bird.||Lieutenant.||Archibald McMurdo.|
|John Sibbald.||Charles G. Phillips.|
|James F. L. Wood.||Joseph W. Kay.|
|Master.||Charles T. Tucker.||Master.||Pownall P. Cotter (acting).|
|Surgeon.||Robert McCormick.||Surgeon.||John Robertson.|
|Purser.||Thomas R. Hallett.||Clerk in Charge.||George H. Moubray.|
|Mate.||Alexander J. Smith.||Mate.||Peter A. Scott.|
|Henry Oakeley.||Thomas E. L. Moore.|
|Joseph Dayman.||William Molloy.|
|Assistant Surgeon.||Joseph D. Hooker.||Assistant Surgeon.||David Lyall.|
|Second Master.||Henry B. Yule.||Second Master.||John E. Davis.|
The complement of each ship amounting to sixty-four persons.
Every improvement that former experience could suggest in preparing the ships for the service, and contributing to the health, comfort, and safety of their crews, was granted by the Admiralty; and from Mr. Rice, of Chatham Dock Yard, to whom I am indebted for the memorandum of the fittings of the Erebus at Chatham Dock, inserted in the Appendix, I received that zealous and able assistance which, from his high abilities, but, I regret to say, unrewarded merits, I had reason to expect.
As opportunities might not occur of replenishing our stores and provisions, it was desirable to carry with us as much as we could possibly stow away. Preserved meats, according to Donkin's invention, in consequence of their portability and excellence, formed a large proportion of our provisions; these were chiefly furnished by John Gillon and Co., of Leith, and proved most excellent of their kind. I would, however, suggest to them and others engaged in this branch of trade, that for voyages of several years' duration it would be better that the canisters in which the meats are preserved, should be of a much stouter tin, equal at least to those originally used by Messrs. Donkin and Co., their canisters being liable to rust through when long on board a ship and in hot climates. The following is a list of the quantities supplied by different firms:—
|Meats.||Vegetables.||Soups.||Concent. Soup.||Total Weight.|
and the relative proportion of each of the several kinds is given in the following table, from which it will be seen that no pains or expense were spared to provide the expedition with such provisions as should be most likely not only to preserve the health of their crews, but add greatly to their comfort; nor would the liberality with which our ships were supplied be ill bestowed, if extended to the whole of our navy; indeed, in the end, I believe there would be a considerable saving of expense, and the subject is well deserving the attention of our rulers, if it were upon the score of humanity alone, when the great amount of suffering, disease, and death, that might be averted by furnishing our ships with a large supply of the preserved meats and vegetables is taken into consideration.
A LIST OF ARTICLES SUPPLIED FOR THE USE OF THE
ANTARCTIC EXPEDITION IN THE YEAR 1839.
Warm clothing of the best quality was also furnished to both ships, to be issued gratuitously to the crews whilst employed amongst the ice, to protect them from the severity of the climate, and every arrangement was made in the interior fitting of the vessels that could in any way contribute to the health or comfort of our people.
As soon as our preparations were completed, I received my final instructions from the Lords Commissioners of the Admiralty, which, in accordance with custom, are here inserted:—
By the Commissioners for executing the office of Lord High Admiral of the United Kingdom of Great Britain and Ireland, &c.
Whereas it has been represented to us that the science of magnetism may be essentially improved by an extensive series of observations made in high southern latitudes, and by a comparison of such observations with others made at certain fixed stations, and whereas practical navigation must eventually derive important benefit from every improvement in that science; we have, in consideration of these objects, caused Her Majesty's ships Erebus and Terror to be in all respects prepared for a voyage for carrying into complete execution the purposes above mentioned: and from the experience we have had of your abilities, zeal, and good conduct, we have thought fit to entrust you with the command of the expedition, and to direct Commander Crozier, whom we have appointed to Her Majesty's ship Terror, to follow your orders for his proceedings.
You are therefore required and directed, as soon as both vessels shall be in all respects ready, to put to sea with them, and on your way to your ulterior destination, you will touch at the Island of Madeira, in order to obtain the sea-rates of the several chronometers with which each vessel has been supplied. From thence (but making a short series of observations at the Rock of St. Paul) you will make the best of your way to the Island of St. Helena, where you are to land the observers and the instruments for the fixed magnetic observatory intended for that station.
In approaching that island, and in proceeding from thence to the Cape of Good Hope, you will endeavour to ascertain at what point you cross the curve of least magnetic intensity; the interest attached to the place of which is set forth in the herewith inclosed Report of the council of the Royal Society; and this Report having been drawn up at our especial request, and containing the several objects of scientific inquiry recommended to your attention by that body, you will follow their suggestions, and carry out their views, as far as may be in your power, consistently with the safety of Her Majesty's ships, and with the means we have placed at your disposal.
At the Cape of Good Hope the instruments and observers for the second fixed magnetic observatory are to be carefully landed; and having completed your water, and replaced the stores which you have expended, you are to proceed to the eastward, touching at Marion and Crozet Isles for observations, if the weather and other circumstances should be favourable for that purpose.
As we have provided the expedition with invariable pendulums, and all the necessary apparatus for determining the figure of the earth; and as it is desirable that these observations should be made at several points, more especially in high southern latitudes, it is probable that Kerguelen Island will be found well suited to that purpose, as well as to an extensive series of magnetic and other observations; but the selection of these stations is freely confided to your judgment.
If the operations at Kerguelen Island, or at such other places as you may select, should be completed before the end of February, 1840, you will possibly find the sea sufficiently open to proceed directly to the southward, to examine those places where indications of land have been noticed, and to make the requisite observations on any outlying islands that you may be able to discover; but, at that advanced period of the season, you are cautiously to avoid being beset in the ice, as your early arrival at Van Diemen's Land is of far greater importance to the great object of the expedition than any results you could hope there to obtain.
Should your observations at Kerguelen Island detain you beyond the above specified period, you will have an opportunity of touching at the Islands of St. Paul and Amsterdam, and of proceeding to Van Diemen's Land by whatever course shall appear to you best calculated for inferring the position of the magnetic pole.
At Van Diemen's Land you are to communicate with Lieutenant Governor Sir John Franklin, who will have been instructed to prepare instruments for the third magnetic observatory, which you are to establish in the most advantageous position, and to place in charge of an officer, with a sufficient number of assistants, to enable him to continue uninterruptedly the observations proposed to be made during the period of your absence, making such provision for their victualling and lodging as appears to be most convenient, and not inconsistent with the Naval Regulations.
Having brought this observatory into active operation, you will lose no time in proceeding to Sydney, which, according to the views contained in the before-mentioned Report, will be a station eminently fitted for the determination of all the magnetic elements, and which will hereafter be the centre of reference for every species of local determination.
The remaining winter months may be advantageously employed in visiting New Zealand and the adjacent islands, and in obtaining there as many series of observations as the time will allow, in order to enable you to judge with greater precision of the course to be adopted in the following summer; but taking care to return to Van Diemen's Land by the end of October, to refit Her Majesty's ships, and to prepare them for a voyage to the southward.
In the following summer, your provisions having been completed and your crews refreshed, you will proceed direct to the southward, in order to determine the position of the magnetic pole, and even to attain to it if possible, which it is hoped will be one of the remarkable and creditable results of this expedition. In the execution, however, of this arduous part of the service entrusted to your enterprise and to your resources, you are to use your best endeavours to withdraw from the high latitudes in time to prevent the ships being beset with the ice; but if, notwithstanding your efforts, they should be cut off from a timely retreat, you are to select the safest inlet you can find for the security of Her Majesty's ships during the winter; and you will house in the ships, and further take every possible precaution for the health and comfort of the officers and crews, which your former experience in the northern expeditions may suggest to you, and for which you have been supplied with abundant means. Having provided for these two most important objects, you will endeavour to turn your detention there to the best account, by sedulously pursuing the different series of observations which the fixed observatories will, at that time, be carrying on in concert with yours.
Should the expedition have been able to avoid wintering in a high latitude, you will return to Van Diemen's Land, availing yourself of every opportunity you can seize of pursuing there, or in such other places as your deliberate judgment may prefer, those series of observations and experiments best adapted to carrying out the leading objects of the expedition.
On the breaking up of the succeeding winter, you will resume the examination of the antarctic seas in the highest latitude you can reach, and proceeding to the eastward from the point at which you had left off the preceding year, you will seek for fresh places on which to plant your observatory in all directions from the pole.
In the event of finding any great extent of land, you will, as far as may be practicable, lay down the prominent parts of its coast line; and you will endeavour not only to correct the positions of Graham Land and Enderby Land, and other places which have been seen only at a distance, but to obtain some knowledge of the nature of those yet unvisited tracts for geographical research; and the magnetic objects of your voyage may be so conducted as mutually to assist each other. With this view we have directed the hydrographer to furnish you with such parts of the instructions usually given to surveying vessels as may lead to the more clear and satisfactory expression of those shores which you may have to examine.
The South Shetlands, or the Orkneys, or perhaps the Sandwich Islands, and lastly, the Falklands, will probably terminate your magnetic labours in the antarctic seas; and if at those latter islands you should not receive further orders from us, you will return to England by such a route as you may think most conducive to the ruling object of the expedition.
In an enterprise of the nature which has been briefly stated in these orders, much must be left to the discretion, temper, and judgment of the commanding officer; and we fully confide in your combined energy and prudence for the successful issue of a voyage, which will engross the attention of the scientific men of all Europe. At the same time we desire you constantly to bear in mind our anxiety for the health, the safety, and the comfort of the officers and crew entrusted to your care.
We also caution you against allowing the two vessels to separate; and we direct you to appoint, not only a sufficient number of well-chosen rendezvous, but to keep up the most unreserved communication with the Commander of the Terror, placing in him every proper confidence, furnishing him with a copy of these orders, and acquainting him from time to time with all your views and intentions for the execution of them; so that the service may not only have the full benefit of your united efforts in its prosecution, but that in case of unavoidable separation, or of any accident to yourself, he may have the advantage of knowing, up to the latest period, all your ideas and intentions.
We also recommend that a frequent change should take place of the observations made in the two ships, in order that any scientific discovery made by the one, should be quickly communicated to the other, as well for their advantage and guidance in making their future observations, as for the purpose of more certainly ensuring their preservation.
In the event of any irreparable accident happening to either ship, and the removal of the crew to the other, the officers and men are hereby authorised to perform their several duties in their respective ranks and stations, in the vessel to which they may be transferred; and should the Erebus be the one disabled, you are in that case to take command of the Terror.
In the event of any fatal accident to yourself, Commander Crozier is hereby authorised to take command of the expedition, either on board the Erebus or Terror, as he may prefer (placing the senior lieutenant in command of the other ship), to carry these instructions into execution.
In the event of England being involved in hostilities with any other power during your absence, you are clearly to understand that you are not to commit any hostile act whatever; the expedition under your command being fitted out for the sole purpose of scientific discoveries, and it being the established practice of all civilised nations to consider vessels so employed as exempt from the operations of war. Confiding in this general feeling, we trust that you would receive assistance from the ships and subjects of any foreign power with which you might fall in; but, if the case should arise, special application to that effect will be made to the respective governments.
While employed in the services stated in these orders, you will take every opportunity of acquainting our secretary, for our information, of your progress; and on your arrival in England, you are forthwith to repair to this office in order to lay before us a full account of your proceedings, taking care before you leave the ship to demand from the officers and all other persons on board, the logs and journals they had kept, and the charts, drawings, and observations which they had made, and which are all to be sealed up; and you will issue similar directions to Commander Crozier and his officers, &c.; the said logs, journals, and other documents to be thereafter disposed of as we may think proper to determine. You will also receive our future directions for the disposal of all such specimens of the animal, vegetable, and mineral kingdoms as in the course of the voyage may have been collected by any person on board of either of the ships, and which you are to endeavour to preserve, as far as may be done without inconvenience.
Given under our hands, the 14th day of September, 1839.
S. John Brooke Pechell.
To James Clark Ross, Esquire,
Captain of H. M. S. Erebus, at Chatham.
By Command of their Lordships,
The Report of the Council of the Royal Society alluded to in my instructions, contained a detailed account of every object of inquiry which the diligence and science of the several committees of that learned body could devise. It occupies a small volume of one hundred pages, so that it is only possible to insert in this place their instructions upon the subject of Terrestrial Magnetism, which is described as the most important, and which is considered as the great scientific object of the expedition.
The president and council of the Royal Society having recommended to Her Majesty's government the equipment of an antarctic expedition for scientific objects, were informed by the Lords Commissioners of the Admiralty that it had been determined to send out Captain James Clark Ross on such an expedition, and the council were at the same time requested to communicate to them, for their information, any suggestions on those subjects, or on other points to which they might wish Captain Ross's attention to be called, in preparing the instructions to that officer. The council, having due regard to the magnitude and importance of the question submitted to them, considered that they would best fulfil the wishes of Her Majesty's Government by a subdivision of the inquiry into different parts, and by referring the separate consideration of each part to distinct committees, consisting of those members of the society who were especially conversant with the particular branches of science to which each division of the inquiry had relation. These several committees, namely, those of physics, of meteorology, of geology and mineralogy, of botany and vegetable physiology, and of zoology and animal physiology, after bestowing much time and great attention in the investigation of the subjects brought under their notice, have each drawn up very full and complete reports of the results of their labours. These reports have been considered and adopted by the council, and have been incorporated in the following General Report, which the council present as their opinion on the matters which have been referred to them by Her Majesty's Government. They take this opportunity of declaring their satisfaction at the prospect of the benefits which are likely to accrue to science from the expedition thus liberally undertaken by the government on the representations made to them by the Royal Society and other scientific bodies in this country, and in conformity with a wise and enlightened policy. They also desire to express their grateful sense of the prompt attention which has been uniformly paid to their suggestions, and of the ample provision which has been made for the accomplishment of the various objects of the expedition.
- Royal Society, 8th August, 1839.
Section 1.—PHYSICS AND METEOROLOGY.
The Council of the Royal Society are very strongly impressed with the number and importance of the desiderata in physical and meteorological science, which may wholly or in part be supplied by observations made under such highly favourable and encouraging circumstances as those afforded by the liberality of Her Majesty's Government on this occasion. While they wish therefore to omit nothing in their enumeration of those objects which appear to them deserving of attentive inquiry on sound scientific grounds, and from which consequences may be drawn of real importance, either for the settlement of disputed questions, or for the advancement of knowledge in any of its branches,—they deem it equally their duty to omit or pass lightly over several points which, although not without a certain degree of interest, may yet be regarded in the present state of science rather as matters of abstract curiosity than as affording data for strict reasoning; as well as others, which may be equally well or better elucidated by inquiries instituted at home and at leisure.
1. Terrestrial Magnetism.
The subject of most importance, beyond all question, to which the attention of Captain James Clark Ross and his officers can be turned,—and that which must be considered as, in an emphatic manner, the great scientific object of the Expedition,—is that of Terrestrial Magnetism; and this will be considered: 1st, as regards those accessions to our knowledge which may be supplied by observations to be made during the progress of the Expedition, independently of any concert with or co-operation of other observers; and 2ndly, as regards those which depend on and require such concert; and are therefore to be considered with reference to the observations about to be carried on simultaneously in the fixed magnetic observatories, ordered to be established by Her Majesty's Government with this especial view, and in the other similar observatories, both public and private, in Europe, India, and elsewhere, with which it is intended to open and maintain a correspondence.
Now it may be observed, that these two classes of observations naturally refer themselves to two chief branches into which the science of terrestrial magnetism in its present state subdivides itself, and which bear a certain analogy to the theories of the elliptic movements of the planets, and of their periodical and secular perturbations. The first comprehends the actual distribution of the magnetic influence over the globe, at the present epoch, in its mean or average state, when the effects of temporary fluctuations are either neglected or eliminated by extending the observations over a sufficient time to neutralise their effects. The other comprises the history of all that is not permanent in the phenomena, whether it appear in the form of momentary, daily, monthly, or annual change and restoration, or in progressive changes not compensated by counter changes, but going on continually accumulating in one direction, so as in the course of many years to alter the mean amount of the quantities observed. These last-mentioned changes hold the same place, in the analogy above alluded to, with respect to the mean quantities and temporary fluctuations, that the secular variations in the planetary movements must be regarded as holding, with respect to their mean orbits on the one hand, and their perturbations of brief period on the other.
There is, however, this difference, that in the planetary theory all these varieties of effect have been satisfactorily traced up to a single cause, whereas in that of terrestrial magnetism this is so far from being demonstrably the case, that the contrary is not destitute of considerable probability. In fact, the great features of the magnetic curves, and their general displacements and changes of form over the whole surface of the earth, would seem to be the result of causes acting in the interior of the earth, and pervading its whole mass; while the annual and diurnal variations of the needle, with their train of subordinate periodical movements, may, and very probably do, arise from, and correspond to electric currents produced by periodical variations of temperature at its surface, due to the sun's position above the horizon, or in the ecliptic, modified by local causes; while local or temporary electric discharges, due to thermic, chemical, or mechanical causes, acting in the higher regions of the atmosphere, and relieving themselves irregularly or at intervals, may serve to render account of those unceasing, and as they seem to us casual movements, which recent observations have placed in so conspicuous and interesting a light. The electrodynamic theory, which refers all magnetism to electric currents, is silent as to the causes of those currents, which may be various, and which only the analysis of their effects can teach us to regard as internal, superficial, or atmospheric.
It is not merely for the use of the navigator that charts, giving a general view of the lines of Magnetic Declination, Inclination, and Intensity, are necessary. Such charts, could they really be depended on, and were they in any degree complete, would be of the most eminent use to the theoretical inquirer, not only as general directions in the choice of empirical formulæ, but as powerful instruments for facilitating numerical investigation, by the choice they afford of data favourably arranged; and above all, as affording decidedly the best means of comparing any given theory with observation. In fact, upon the whole, the readiest, and beyond comparison the fairest and most effectual mode of testing the numerical applicability of a theory of terrestrial magnetism, would be, not servilely to calculate its results for given localities, however numerous, and thereby load its apparent errors with the real errors, both of observation and of local magnetism; but to compare the totality of the lines in our charts with the corresponding lines, as they result from the formulæ to be tested, when their general agreement or disagreement will not only show how far the latter truly represents the facts, but will furnish distinct indications of the modifications they require.
Unfortunately for the progress of our theories, however, we are yet very far from possessing charts even of that one element, the Declination, most useful to the navigator, which satisfy these requisites; while as respects the others (the Inclination and Intensity) the most lamentable deficiencies occur, especially in the Antarctic regions. To make good these deficiencies by the continual practice of every mode of observation appropriate to the circumstances in which the observer is placed throughout the voyage, will be one of the great objects to which attention must be directed. And first—
At sea.—We are not to expect from magnetic observations made at sea the precision of which they are susceptible on land. Nevertheless, it has been ascertained that not only the Declination, but the Inclination and Intensity, can be observed, in moderate circumstances of weather and sea, with sufficient correctness, to afford most useful and valuable information, if patience be bestowed, and proper precautions adopted. The total intensity, it is ascertained, can be measured with some considerable degree of certainty by the adoption of a statical method of observation recently devised by Mr. Fox, whose instrument will be a part of the apparatus provided. And when it is recollected that but for such observations the whole of that portion of the globe which is covered by the ocean must remain for ever a blank in our charts, it will be needless further to insist on the necessity of making a daily series of magnetic observations, in all the three particulars above-mentioned, whenever weather and sea will permit, an essential feature in the business of the voyage, in both ships. Magnetic observations at sea will, of course, be affected by the ship's magnetism, and this must be eliminated to obtain results of any service. To this end,
First. Every series of observations made on board should be accompanied with a notice of the direction by compass of the ship's head at the time.
Secondly. Previous to sailing, a very careful series of the apparent deviations, as shown by two compasses permanently fixed, (the one as usual, the other in a convenient position, considerably more forward in the ship,) in every position of the ship's head, as compared with the real position of the ship, should be made and recorded, with a view to attempt procuring the constants of the ship's action according to M. Poisson's theory; and this process should be repeated on one or more convenient occasions during the voyage; and, generally, while at anchor, every opportunity should be taken of swinging round the ship's head to the four cardinal points, and executing in each position a complete series of the usual observations.
Thirdly. Wherever magnetic instruments are landed and observations made on terra firma, or on ice, the opportunity should be seized of going through the regular series on shipboard with more than usual diligence and care, so as to establish by actual experiment in the only unexceptionable manner the nature and amount of the corrections due to the ship's action for that particular geographical position, and by the assemblage of all such observations to afford data for concluding them in general.
Fourthly. No change possible to be avoided should be made in the disposition of considerable masses of iron in the ships during the whole voyage; but if such change be necessary, it should be noted.
Fifthly. When crossing the magnetic line of no dip it would be desirable to go through the observation for the dip with the instrument successively placed in a series of different magnetic azimuths, by which the influence of the ship's magnetism in a vertical direction will be placed in evidence.
On land, or on ice.—As the completeness and excellence of the instruments with which the expedition will be furnished will authorise the utmost confidence in the results obtained by Captain Ross's well-known scrupulosity and exactness in their use, the redetermination of the magnetic elements at points where they are already considered as ascertained, will be scarcely less desirable than their original determination at stations where they have never before been observed. This is the more to be insisted on, as lapse of time changes these elements in some cases with considerable rapidity; and it is therefore of great consequence that observations to be compared should be as nearly cotemporary as possible, and that data should be obtained for eliminating the effects of secular variations during short intervals of time, so as to enable us to reduce the observations of a series to a common epoch.
On the other hand it cannot be too strongly recommended, studiously to seek every opportunity of landing on points (magnetically speaking) unknown, and determining the elements of those points with all possible precision. Nor should it be neglected, whenever the slightest room for doubt subsists, to determine at the same time the geographical position of the stations of observation in latitude and longitude. When the observations are made on ice, it is needless to remark that this will be universally necessary.
With this general recommendation it will be unnecessary to enumerate particular localities. In fact it is impossible to accumulate too many. Nor can it be doubted that in the course of antarctic exploration, many hitherto undiscovered points of land will be encountered, each of which will, of course, become available as a magnetic station, according to its accessibility and convenience.
There are certain points in the regions about to be traversed in this voyage which offer great and especial interest in a magnetic point of view. These are, first, the south magnetic pole (or poles), intending thereby the point or points in which the horizontal intensity vanishes and the needle tends vertically downwards; and secondly, the points of maximum intensity, which, to prevent the confusion arising from a double use of the word poles, we may provisionally term magnetic foci.
It is not to be supposed that Captain Ross, having already signalised himself by attaining the northern magnetic pole, should require any exhortation to induce him to use his endeavours to reach the southern. On the contrary, it might better become us to suggest for his consideration, that no scientific datum of this description, nor any attempt to attain very high southern latitudes, can be deemed important enough to be made a ground for exposing to extraordinary risk the lives of brave and valuable men. The magnetic pole, though not attained, will yet be pointed to by distinct and unequivocal indications; viz. by the approximation of the dip to 90°; and by the convergence of the magnetic meridians on all sides towards it. If such convergence be observed over any considerable region, the place of the pole may thence be deduced, though its locality may be inaccessible.
M. Gauss, from theoretical considerations, has recently assigned a probable position in Ion. 146° E., lat. 66° S. to the southern magnetic pole, denying the existence of two poles of the same name, in either hemisphere, which, as he justly remarks, would entail the necessity of admitting also a third point, having some of the chief characters of such a pole intermediate between them. That this is so may be made obvious without following out his somewhat intricate demonstration, by simply considering, that if a needle be transported from one such pole to another of the same name, it will begin to deviate from perpendicularity towards the pole it has quitted, and will end in attaining perpendicularity again, after pointing in the latter part of its progress obliquely towards the pole to which it is moving, a sequence of things impossible without an intermediate passage through the perpendicular direction.
It is not improbable that the point indicated by M. Gauss will prove accessible; at all events it cannot but be approachable sufficiently near to test by the convergence of meridians the truth of the indication; and as his theory gives within very moderate limits of error the true place of the northern pole, and otherwise represents the magnetic elements in every explored region with considerable approximation, it is but reasonable to recommend this as a distinct point to be decided in Captain Ross's voyages. Should the decision be in the negative, i.e. should none of the indications characterising the near vicinity of the magnetic pole occur in that region, it will be to be sought; and a knowledge of its real locality will be one of the distinct scientific results which may be confidently hoped from this expedition, and which can only be attained by circumnavigating the antarctic pole compass in hand.
The actual attainment of a focus of maximum intensity is rendered difficult by the want of some distinct character by which it can be known, previous to trial, in which direction to proceed, when after increasing to a certain point the intensity begins again to diminish. The best rule to be given, would be (supposing circumstances would permit it) on perceiving the intensity to have become nearly stationary in its amount, to turn short and pursue a course at right angles to that just before followed, when a change could not fail to occur, and indicate by its direction towards which side the focus in question were situated.
Another, and as it would appear, a better mode of conducting such a research, would be, when in the presumed neighbourhood of a focus of maximum intensity, to run down two parallels of latitude or two arcs of meridians separated by an interval of moderate extent, observing all the way in each, by which observations when compared, the concavities of the isodynamic lines would become apparent, and perpendiculars to the chords, intersecting in or near the foci, might be drawn.
Two foci or points of maximum total intensity are indicated by the general course of the lines in Major Sabine's chart in the southern hemisphere, one about long. 140° E., lat. 47° S., the other more obscurely in long. 235° E., lat. 60° S. or thereabouts. Both these points are certainly accessible; and as the course of the expedition will lead not far from each of them, they might be visited with advantage by a course calculated to lead directly across the isodynamic ovals surrounding them.
Pursuing the course of the isodynamic lines in the chart above mentioned, it appears that one of the two points of minimum total intensity, which must exist, if that chart be correct, may be looked for nearly about lat. 25° S., long. 12° W., and that the intensity at that point is probably the least which occurs over the whole globe. Now this point does not lie much out of the direct course usually pursued by vessels going to the Cape. It would therefore appear desirable to pass directly over it, were it only for the sake of determining by direct measure the least magnetic intensity at present existing on the earth, an element not unlikely to prove of importance in the further progress of theoretical investigation. Excellent opportunities will be afforded for the investigation of all these points, and for making out the true form of the isodynamic ovals of the South Atlantic, both in beating up for St. Helena, and in the passage from thence to the Cape; in the course of which, the point of least intensity will, almost of necessity, have to be crossed, or at least approached very near.
Nor is the theoretical line indicated by Gauss as dividing the northern and southern regions, in which free magnetism may be regarded as superficially distributed, undeserving of attention. That line cuts the equator in 6° east longitude, being inclined thereto (supposing it a great circle) 15°, by which quantity it recedes from the equator northward in going towards the west of the point of intersection. Observations made at points lying in the course of this line may hereafter prove to possess a value not at present contemplated.
As a theoretical datum, the horizontal intensity has been recommended by Gauss, in preference to the total, not only as being concluded from observations susceptible of great precision, but as affording immediate facilities for calculation. As it cannot now be long before the desideratum of a chart of the horizontal intensity is supplied, the maxima and minima of this element may also deserve especial inquiry, and may be ascertained in the manner above pointed out.
The maxima of horizontal intensity are at present undetermined by any direct observation. They must of necessity however, lie in lower magnetic latitudes than those of the total intensity, as its minima must in higher, and from such imperfect means as we have of judging, the conjectural situations of the maxima may be stated as occurring in
Observations have been made of the horizontal intensity in the vicinities of II. and III., and are decidedly the highest which have been observed anywhere.
In general, in the choice of stations for determining the absolute values of the three magnetic elements, it should be borne in mind, that the value of each new station is directly proportional to its remoteness from those already known. Should any doubt arise, therefore, as to the greater or less eligibility of particular points, a reference to the existing magnetic maps and charts, by showing where the known points of observation are most sparingly distributed, will decide it.
For such magnetic determinations as those above contemplated, the instruments hitherto in ordinary use, with the addition of Mr. Fox's apparatus for the statical determination of the intensity, will suffice; the number of the sea observations compensating for their possible want of exactness. The determinations which belong to the second branch of our subject,—viz. those of the diurnal and other periodical variations, and of the momentary fluctuations of the magnetic forces,—require, in the present state of our knowledge, the use of those more refined instruments recently introduced. Being comparative rather than absolute, they depend in great measure (and as regards the momentary changes, wholly) on combined and simultaneous observation.
The variations to which the earth's magnetic force is subject, at a given place, may be classed under three heads, namely, 1. the irregular variations, or those which apparently observe no law; 2. the periodical variations, whose amount is a function of the hour of the day, or of the season of the year; and 3. the secular variations, which are either slowly progressive, or else return to their former values in periods of very great and unknown magnitude.
The recent discoveries connected with the irregular variations of the magnetic declination, have given to this class of changes a prominent interest. In the year 1818, M. Arago made, at the Observatory of Paris, a valuable and extensive series of observations on the declination changes; and M. Kupffer having about the same time undertaken a similar research at Cazan, a comparison of the results led to the discovery that the perturbations of the needle were synchronous at the two places, although these places differed from one another by more than forty-seven degrees of longitude. This seems to have been the first recognition of a phenomenon, which now, in the hands of Gauss and those who are labouring with him, appears likely to receive a full elucidation.
To pursue this phenomenon successfully, and to promote in other directions the theory of terrestrial magnetism, it was necessary to extend and vary the stations of observation, and to adopt at all a common plan. Such a system of simultaneous observations was organized by Von Humboldt in the year 1827. Magnetic stations were established at Berlin and Freyberg: and the Imperial Academy of Russia entering with zeal into the project, the chain of stations was carried over the whole of that colossal empire. Magnetic houses were erected at Petersburgh and at Cazan; and magnetic instruments were placed, and regular observations commenced, at Moscow, at Sitka, at Nicolajeff in the Crimea, at Barnaoul and Nertschinsk in Siberia, and even at Pekin. The plan of observation was definitely organized in 1830; and simultaneous observations were made seven times in the year, at intervals of an hour for the space of forty-four hours.
In 1834, the illustrious Gauss turned his attention to the subject of terrestrial magnetism; and having contrived instruments which were capable of yielding results of an accuracy before unthought of in magnetic researches, he proceeded to inquire into the simultaneous movements of the horizontal needle at distant places. At the very outset of his inquiry he discovered the fact, that the synchronism of the perturbations was not confined (as had been hitherto imagined) to the larger and extraordinary changes; but that even the minutest deviation at one place of observation had its counterpart at the other. Gauss was thus led to organize a plan of simultaneous observations, not at intervals of an hour, but at the short intervals of five minutes. These were carried on through twenty-four hours six times in the year; and magnetic stations taking part in the system were established at Altona, Augsburg, Berlin, Bonn, Brunswick, Breda, Breslau, Cassel, Copenhagen, Dublin, Freyberg, Göttingen, Greenwich, Halle, Kazan, Cracow, Leipsic, Milan, Marburg, Munich, Naples, St. Petersburg, and Upsala.
Extensive as this plan appears, there is much yet remaining to be accomplished. The stations, numerous as they are, embrace but a small portion of the earth's surface; and what is of yet more importance, none of them are situated in the neighbourhood of those singular points or curves on the earth's surface, where the magnitude of the changes may be expected to be excessive, and perhaps even their direction inverted. In short, a wider system of observation is required to determine whether the amount of the changes (which is found to be very different in different places) is dependent simply on the geographical or on the magnetic co-ordinates of the place; whether, in fact, the variation in that amount be due to the greater or less distance of a disturbing centre, or to the modifying effect of the mean magnetic force of the place, or to both causes acting conjointly. In another respect also, the plan of the simultaneous observations admits of a greater extension. Until lately the movements observed have been only those of the magnetic declination, although there can be no doubt that the inclination and the intensity are subject to similar perturbations. Recently, at many of the German stations, the horizontal component of the intensity has been observed, as well as the declination; but the determination of another element is yet required, before we are possessed of all the data necessary in this most interesting research.
The magnetic observations about to be established in the British colonies, by the liberality of the government, will (it is hoped) supply in a great measure these desiderata. The stations are widely scattered over the earth's surface, and are situated at points of prominent interest with regard to the Isodynamic and Isoclinal lines. The point of maximum intensity in the northern hemisphere is in Canada; the corresponding maximum in the southern hemisphere is near Van Diemen's Land; St. Helena is close to the line of minimum intensity; and the Cape of Good Hope is of importance on account of its southern latitude. At each observatory the changes of the vertical component of the magnetic force will be observed, as well as those of the horizontal component and declination; and the variations of the two components of the force being known, those of the inclination and of the force itself are readily deduced. The simultaneous observations of these three elements will be made at numerous and stated periods, and we have every reason to hope that the directors of the various European observatories will take part in the combined system.
But interesting as these phenomena are, they form but a small part of the proper business of an observatory. The regular changes (both periodic and secular) are no less important than the irregular; and they are certainly those by which a patient inductive inquirer would seek to ascend to general laws. Even the empirical expression of those laws cannot fail to be of the utmost value, as furnishing a correction to the absolute values of the magnetic elements, and thereby reducing them to their mean amount.
The hourly changes of the declination have been frequently and attentively observed; but with respect to the periodical variations of the other two elements, our information is as yet very scanty. The determination of these variations will form an important part of the duty of the magnetic observatories; and from the accuracy of which the observations are susceptible, and the extent which it is proposed to give them, there can be no doubt that a very exact knowledge of the empirical laws will be the result.
With respect to the secular variations, it might perhaps be doubted whether the limited time during which the observatories will be in operation is adequate to their determination. But it should be kept in mind that the monthly mean corresponding to each hour of observation will furnish a separate result; and that the number and accuracy of the results thus obtained may be such as fully to compensate for the shortness of the interval through which they are followed. A beautiful example of such a result, deduced from three years' observation of the declination, is to be found in the first volume of Gauss's magnetical work, of which a translation is published in the fifth number of Taylor's Scientific Memoirs.
It remains to say a few words of the instrumental means which have been adopted for the attainment of these ends.
The magnetic instruments belonging to each observatory and in constant use, are, 1. a declination instrument; 2. a horizontal force magnetometer; 3. a vertical force magnetometer. These instruments are constructed after the plan adopted by Professor Lloyd in the Magnetic Observatory of Dublin. The magnet, in the two former, is a heavy bar, fifteen inches long, and upwards of a pound in weight. In the declination instrument the magnet rests in the magnetic meridian, being suspended by fibres of silk without torsion. In the horizontal force magnetometer, the magnet is supported by two parallel wires, and maintained in a position at right angles to the magnetic meridian by the torsion of their upper extremities. In both instruments the changes of position of the magnet are read off by means of an attached collimater having a divided scale in its focus. The magnetometer for the vertical force is a bar resting by knife edges on agate planes, and capable of motion therefore in the vertical plane only. This bar is loaded so as to rest in the horizontal position in the mean state of the force; and the deviations from that position are read off by micrometers near the two extremities of the bar.
In addition to these instruments, each observatory is furnished with a dip circle, a transit with an azimuth circle, and two chronometers. Each vessel also is supplied with a similar equipment. Should therefore the ships be under the necessity of wintering in the ice,—and generally, on every occasion when the nature of the service may render it necessary to pass a considerable interval of time in any port or anchorage,—the magnetometers should be established, and observations made with all the regularity of one of the fixed observatories, and with strict attention to all the same details.
The selection of proper stations for the erection of the magnetometers, and the extent of time which can be bestowed upon each, must in a great measure depend on circumstances which can only be appreciated after the expedition shall have sailed. The observatory at St. Helena (the officers and instruments for which will be landed by Captain Ross) will in all probability,—and that at the Cape (similarly circumstanced in this respect) may possibly,—be in activity by the time the ships arrive at Kerguelen's Land, which we would recommend as a very interesting station for procuring a complete and as extensive a series of corresponding observations as the necessity of a speedy arrival at Van Diemen's Land for the establishment of the fixed observatory at that point will allow; taking into consideration the possibility of obtaining during the intermediate voyage a similar series at some point of the coast discovered by Kemp and Biscoe. In the ulterior prosecution of the voyage, a point of especial interest for the performance of similar observations will be found in New Zealand, which, according to the sketch of the voyage laid before us by Captain Ross, will probably be visited shortly after the establishment of the Van Diemen's Land observatory. The observations there will have especial interest, since, taken in conjunction with those simultaneously making in Van Diemen's Land, they will decide the important question, how far that exact correspondence of the momentary magnetic perturbations which has been observed in Europe, obtains in so remote a region, between places separated by a distance equal to that between the most widely distant European stations.
In the interval between quitting Van Diemen's Land and returning to it again, opportunities will no doubt occur of performing more than one other series of magnetometer observations, the locality of which may be conveniently left to the judgment of Captain Ross, bearing in mind the advantage of observing at stations as remote as possible from both Van Diemen's Land and New Zealand.
The research for the southern magnetic pole and the exploration of the antarctic seas will afford, it may be presumed, many opportunities of instituting on land hitherto unknown, or on firm ice when the vessel may be for a time blockaded, observations of this description; and in the progress of the circumnavigation, the line of coast observed or supposed to exist under the name of Graham's Land, or those of the islands in that vicinity, South Shetland, Sandwich Land, and finally on the homeward voyage the Island of Tristan d'Acunha, will afford stations each of its own particular interest.
A programme will be furnished of the days selected for simultaneous observations at the fixed observatories, and of the details to be attended to in the observations themselves as above alluded to. These days will include the terms or stated days of the German Magnetic Association, in which, by arrangements already existing, every European magnetic observatory is sure to be in full activity. These latter days, which occur four times in the year, will be especially interesting, as periods of magnetometrical observations by the expedition, when the circumstances of the voyage will permit. For the determination of the existence and progress of the diurnal oscillation, in so far as that important element can be ascertained in periods of brief duration, it will be necessary to continue the observations hourly during the twenty-four for not less than one complete week. At every station where the magnetometers are observed, the absolute values of the dip, horizontal direction, and intensity will require to be ascertained.
Sydney, for a station of absolute determinations, would be with great propriety selected, as there can be no doubt of its becoming at no distant period a centre of reference for every species of local determination.
The meteorological particulars to be chiefly attended to, as a part of the magnetic observations, are those of the barometer, thermometer, wind, and especially auroras, if any. In case of the occurrence of the latter indeed, the hourly should at once be exchanged for uninterrupted observation, should that not be actually in operation. The affections of the magnetometers during thunder-storms, if any, should be noticed, though it is at present believed that they have no influence.
During an earthquake in Siberia in 1829, the direction of the horizontal needle, carefully watched by M. Erman, was uninfluenced; should a similar opportunity occur, and circumstances permit, it should not be neglected.
Should land or secure ice be found in the neighbourhood of the magnetic pole, every attention will of course be paid to the procuring a complete and extensive series of magnetometric observations, which in such a locality would form one of the most remarkable results of the Expedition.
The other objects of inquiry recommended by the Committee of Physics and Meteorology are enumerated in the following summary of the Report:—
1. Magnetic observations of the inclination, declination, and intensity at sea, throughout the voyage, daily in both ships, whenever the motion of the vessel will permit.
2. Precise determinations of the same particulars wherever the expedition may land, or disembark on ice.
3. Most careful series of magnetometric observations, in correspondence with those to be made at the fixed observatories, according to a plan concerted with the officers of those observatories, and with Professor Lloyd, the particulars of which will be furnished to each party concerned, and distributed to all the European and other observatories.
4. A circumnavigation of the Antarctic Pole, with a view to affording opportunities and proper stations for magnetic and other observations.
5. An inquiry into the actual position of the southern magnetic pole or poles, and the points or foci of greatest and least total and horizontal intensity, and into the course and figure of the isodynamic ovals presumed to occupy the area of the South Atlantic.
6. The determination of the length of the invariable pendulum at several stations in high south latitudes.
7. Observations of the tides, i.e. of the heights and times of high water, made at such stations at which the ships may remain long enough, and at which the correct establishment is unknown.
8. The keeping of a regular meteorological register in both ships during the whole voyage, and the paying attention to the phenomena of solar and terrestrial radiation, and generally to all phenomena bearing on the subject of meteorology.
9. The temperature of the sea at the surface and at stated moderate depths should be observed as frequently as possible, and whenever opportunity may occur, also at the greatest depths attainable; and attention should be directed to the temperature of currents and shoals, as well as to its variation on approaching land. The temperature of the soil at various depths should be taken on landing, as well as that of springs, wells, &c.
10. Soundings should be attempted in deep seas, and specimens of the water brought up be preserved for future examination.
11. Observations should be collected of the aurora in high south latitudes; and attention directed to meteors and shooting stars on those occasions when experience has shown that they occur periodically in great abundance; as well as to the appearance of the zodiacal light, and other phenomena of a similar occasional nature.
12. Observations of the comparative brightness of southern stars should be procured, and especially of the variable stars α Hydræ and η Argûs.
13. The amount and laws of horizontal refraction, both celestial and terrestrial, in high south latitudes, should be investigated.
14. The phenomena of eclipses should be attended to.
The Geological, Zoological, and Botanical Committees also drew up catalogues of desiderata, with full instructions for the collection and preservation of specimens of the animal, vegetable, and mineral kingdoms; and the Admiralty furnished us with ample means for carrying out their several recommendations.
The two former collections were undertaken by Mr. McCormick and Mr. Robertson, in addition to their duties as chief medical officer of each ship; and for the diligence and zeal with which they performed their task, my thanks are especially due; as also to Dr. Joseph D. Hooker and Mr. Lyall, whose unceasing exertions in the botanical department have contributed several thousand new genera and species to the catalogues of the Southern Flora.
To Mr. McCormick and Dr. Hooker I am besides indebted for several very interesting notices of the geology and botany of the places visited by the Expedition, which are inserted either in the narrative or the Appendix.
The drawings and vignettes contained in these volumes were principally furnished by Mr. Davis; those of Christmas Harbour, Nine Pin Rock, and deep soundings, by Lieutenant Dayman; and some, which bear his name, by Dr. Hooker.
I have also to express my deep obligations to Dr. Sir John Richardson, of Haslar Hospital, and J. E. Gray, Esq., of the British Museum, for undertaking, gratuitously, the publication of an account of the zoological collection formed during the course of our voyage; and to those gentlemen of the British Museum who have assisted them in the laborious task; and to Dr. Hooker, for the elaborate manner in which he is describing the extensive botanical collection in the beautifully executed "Flora Antarctica."
For the illustration of these two great works, which are now advancing towards completion, the government, at the recommendation of the Lords Commissioners of the Admiralty, granted the sum of two thousand pounds; and I hope that naturalists will at once appreciate the liberality of this measure, and acknowledge that the money has been advantageously employed.
It has been impossible, in the course of the narrative, to do more than glance at some of the important scientific results of the expedition; but the whole of the observations are in course of publication, chiefly in the Philosophical Transactions of the Royal Society. Under the able supervision of Colonel Sabine, nearly all relating to terrestrial magnetism, which were transmitted by me, as opportunities offered, to England, have already appeared; and the magnetometric portion of them, in a separate volume, is in a forward state of preparation. The expense of these publications has been also defrayed by the government.
I am also indebted to Admiral Beaufort for the kind assistance he has given me in the construction of the plans and charts contained in these volumes; to Mr. Davis, of the Terror, by whom they were drawn from my original documents; and to the Messrs. Walker, for the accuracy and beauty with which they have been engraved.
Indeed, I am unable to express the gratitude I feel to those gentlemen who have so generously come forward to afford their gratuitous assistance in the publication of the accumulated labours of the Expedition: in their hands I feel assured that full justice will be done to the several subjects under their discussion, and that when all shall have been completed, I think it will be acknowledged that the Expedition has accomplished the more important objects for which it was sent forth.
JAMES C. ROSS.
Aston House, Aylesbury,
June 1. 1847.
- Quarterly Review, No. CXXXI. p. 297. June, 1840.
- This request was conveyed in a letter from Sir John Barrow, addressed to the secretary of the Royal Society, and dated June 13. 1839.
- Recently reduced to four.