Popular Science Monthly/Volume 2/January 1873/Astronomical and Physical Observatories
|ASTRONOMICAL AND PHYSICAL OBSERVATORIES.|
IT has been said that "dirt is but matter out of place," and we may likewise take for an axiom that error is force misapplied. It cannot be complained that the age in which we live is one which demands the most careful economy of our forces of all kinds, nor are we intellectually in the position which geologists are fond of predicting for the material world—"nearly out of our store of force." But it were wisdom in us to husband the forces we have, that we may hand down to our successors a thoroughly well-ordered system in all things. And in nothing should we be so careful and scrupulous as in our schemes of education, which affect, in a very direct way, the judgment of the generation which follows us.
Sooner or later there is created in most American colleges what is thereafter known as its astronomical observatory, and in respect to this portion of the college we are frequently called on to lament over some glaring instances of wasted force—force misapplied. One of the forms of these prevalent errors is a mania for "instruments of the largest size," which are not unfrequently bought at large cost, and used perhaps a dozen times a year to allow the senior class, and perchance a few ladies, to view such objects as Jupiter, Saturn, the moon, perhaps a double star, and, more unlikely yet, a nebula. Its kindred error is an immense and vague desire for the multiplication of apparatus, so that one walks amid a labyrinth of chronographs, transits, meridian circles, and equatorials, upon each of which the rust of long inaction lies. We must remember that each of these instruments represents a large outlay of money, and also an expenditure of faith in the giver of them. It is bad enough to allow so much mere capital to lie idle, but it is worse not to return to the benefactor of a college something which may be the sign of a good investment, something which shall encourage him and others to believe that their gifts are doing real, practical educational good. It is here intended to speak only of the college observatory as a means of education, and a distinct difference is made between the ordinary institution of this kind, and the working observatories of such colleges as Dartmouth, Harvard, the University of Michigan, and others.
It is taken for granted that the ordinarily-constituted observatory is for the purpose of teaching certain specific things and certain important methods to the average class of college pupils, and it will be the endeavor of this paper to point out a remedy for some of the abuses that undoubtedly exist in this respect.
Most certainly there are but few subjects which have a greater educational value than Astronomy. As a continuation of the most advanced mathematical course, Theoretical Astronomy is of immense importance and of endless extent. The effect of its study upon the mind is of a much higher order, most of us will agree nowadays, whatever Pythagoras might have said, than the study of even the most abstract relations of number and space. It is supplementary to these last-named subjects, which are, so to say, its raw material, which it elaborates into more complex and higher forms. But let us remember, it is the boast of Theoretical Astronomy that it is purely a science of the closet, dependent upon observation only for its data. Its greatest master, Laplace, thus speaks in the "Système du Monde:" "II est très remarquable qu'un Astronome, sans sortir de son observatoire, en comparant seulement ses observations à l'analyse, eût pu déterminer exactement la grandeur et l'aplatissernent de la terre, et sa distance au soleil et a la lune, éléments dont la connaissance a été le fruit de longs et sensibles voyages dans les deux hémispheres," etc. (6me edition, p. 232).
It is evidently not the purpose of Theoretical Astronomy, then, to train faculties other than those employed in the higher mathematical investigations, and for this purpose no observatory is strictly necessary. But Physical Astronomy, as usually taught, confines itself to Descriptive Astronomy, and for that study it is undoubtedly necessary that students should have access (and a far freer access than they usually have) to instruments. To supply this want, "instruments of the largest size" have been too frequently supplied, so that it is possible that the student may contemplate the features of the moon, or the components of a coarse double star, through a 15-inch, nay, perhaps, a 20-inch object-glass, when perhaps a 4-inch telescope of Alvan Clark's make would serve the student's and the college's purposes fully. It used to be a saying of a celebrated American astronomer that "the price of telescopes increased directly as the cubes of the diameters of their object-glasses." If no higher ratio be the true one, it is evident that in the case supposed we have force misapplied, or not applied at all. It has become almost a reproach for a college not to own an equatorial of at least eight inches clear aperture; yet only consider how much of the best work of astronomy has been done with less apertures! Sir John Herschel and Sir James South executed a long and very refined series of measures of double stars with a much smaller instrument than the ordinary college equatorial, and much of Struve's best work is recorded as done with "the smaller instruments," and so on. It is not intended to advocate the use of poor instruments, nor specially of small ones, but to point out that the means should be adjusted to the object in view, and that no waste of power should be permitted. Again, Spherical Astronomy is taught in some colleges; and, in considering this branch of the subject, we are touching on its most useful portion. In nothing is a student's habit of accuracy more trained than in astronomical observation. There are minor points to be attended to each moment, and it is not until he ceases to be a pupil that he begins to be thoroughly at ease with even the simplest instrument. He has a running commentary of reasoning to make constantly, which is of the greatest value to him. He must constantly ask himself, while using his instruments, "If I do this or that, what will happen, and why?" Now, it is presumably to forward this branch of Astronomy—Spherical Astronomy—that the college observatory was founded, and, if it does this in the right way, it is of great value. To do this properly, requires but a small outlay. A small equatorial of, say, four inches aperture, with circles divided to one minute, will serve to exhibit every thing of interest to the general observer, and will give a student much more opportunity for work than he can possibly find time to improve. A Pistor & Martin's portable meridian circle, two good clocks or chronometers, and, if one wishes luxury, a chronograph, will fit up a small observatory in the most complete way, and give both student and professor excellent means for observation. All this could easily be bought for the price of one of the unwieldy equatorials which lie idle in so many college-towers.
We must remember, too, that the professor of astronomy in most colleges is a busy individual. I have before me the condensed catalogues of 157 American colleges, with an aggregate number of pupils so great as 34,515, and, on running over the lists of college-officers, I find such entries as the following: "—— ——, Professor of Mechanics, Astronomy, and Engineering:" or "Professor of Mathematics, Astronomy, Physics, and Geology:" or of "Astronomy and Physiology;" or, again, of "Latin, Astronomy, and History of American Literature," and many other similar mixtures.
All this indicates that very little time is given by the average student to any proper study of the subject, and the expensive and ill-considered observatories in the country certainly show that a great deal of money and time is wasted in their construction. The writer of this article is familiar with several of such ill-proportioned sets of apparatus. In one case, the observatory contains a fair equatorial of six inches aperture, mounted on a brick arch let into the walls of its tower a few feet below the floor of the dome, which arch receives every tremor of the adjacent building, which is full of students; also a fine portable transit by Würdemann, no clock, and a mean solar chronometer. In another a fine clock is thrown away on a zenith telescope, which is used only as a transit, and so on.
The moral would seem to be to have few instruments, to have them of the best possible workmanship for their size, and to have no one so large and expensive as to prevent the purchase of others which are necessary.
But it is proposed further to give a few reasons why, as a means of education, the astronomical observatory might well, in ordinary cases, be superseded by the physical observatory, or at least why in most cases it would be better to divert some of the funds, which would otherwise be spent on little-used apparatus, to establishing a physical observatory, on a modest basis.
And first let us remember that, to properly educate, we must not only give knowledge, but also the power to acquire knowledge; that, although facts are of great importance, the mental grasp which will connect isolated facts is much more valuable. Viewed in this light, the study of astronomy will be readily seen to be less efficient for training the mind than the study of physics. Physics, indeed, includes astronomy as one of its parts, but, as the term physics is commonly used, it denotes the science of the changes and conditions of terrestrial matter, and peculiarly of the laws relating to the various emanations of celestial bodies, heat, light, etc. The subjects here referred to are such that their study requires in the very highest degree just those faculties which it is the province of modern education to train. Physics, too, is eminently a practical science; it gives the rationale of what we see all around us, and is, so to say, of progressive difficulty. Its elements may be taught to the young lad, and he may go on for his life in their development. Every special method which is useful educationally, that we have referred to in astronomical study, has its analogue here.
Thermo-dynamics and optics certainly present as wide fields for pure analysis as even celestial mechanics. In the cultivation of the powers of observation, the study of physics stands preeminent; and in the physical laboratory the student has an immense advantage, for in many cases it is within his power to produce by experiment, and on a small scale and under favorable conditions, the same appearances that he observes in Nature. There is thus opened to the mind a vast field for that "scientific use of the imagination" which is so important an element in culture.
Perhaps it is more than time that the exact nature of a physical laboratory or observatory should be explained, and we are fortunate in having a succinct account of its main purpose from the hand of Prof. Henry, of the Smithsonian Institution.
Prof. Henry says (Report, 1870, p. 141) the principal object of a physical observatory is, "to investigate the nature and changes of the constitution of the heavenly bodies; to study the various emanations from these, in comparison with the results of experiments, and to record and investigate the different phenomena which are included under the name of terrestrial physics."
The study of the nature and constitution of the sun, by means of photographs, by experiments on its heat, by the spectroscope, and the comparison of these results with similar observations of the stars, is also pointed out by Prof. Henry, as among the legitimate and necessary works of such an institution as he describes. Climatology, meteorology, magnetics, and electrics, equally belong to its scope.
To completely equip such an observatory as we imagine, would require a great outlay, but, considered only in its relation to a college, an equipment becomes much more simple and less expensive. The apparatus required is simple in its nature, and but few of the single instruments are of great cost, and the true policy of a college would be to allow its laboratory to grow slowly with it, enlarging its scope as occasion demanded. In such an observatory the student would acquire every habit of nice adjustment, delicate manipulation, accurate judgment, which would be acquired in the best astronomical observatory, and the field for the mathematical discussion of his results is simply limitless.
In another aspect, too, does the foundation of such observatories hold out important promises. It must be remembered that many of our physical constants rest unfortunately upon too uncertain a basis. The velocity of electricity and the density of the earth are examples. We have to look, then, to scientific men for the establishment of these and other facts as they truly are, and besides, for the discovery of the vast number of unknown physical laws, some of which we must believe are entirely within our reach, and but waiting continued effort to declare themselves. The laws of terrestrial magnetism, the connection of the aurora borealis with other appearances, and like subjects, seem upon the point of being elucidated. It must be remembered, too, that one astronomical observatory can do the routine work for an entire country, and that, once done, it is done forever, and that any repetition of it, however useful it may be to the person making it, is yet of no original value in the world. But the vast number of unclassified facts in the domain of physics, and the almost infinite variety of its unknown laws, will supply ample work for many more physical observatories than could possibly be established. It seems decidedly to the advantage of the student and of the college that each should have the benefit of a well-appointed physical observatory, and it is certain that the class of American gentlemen who found and sustain departments of this kind in our colleges (and it is a very large class, to our honor be it said), will find, in the establishment of such an observatory as we have advocated, the pleasure which comes from effort wisely made. They will see (as they have a most undoubted right to expect to see) the immediate usefulness and benefit of their gift, and can hardly fail to have aided in the discovery of some one of the many laws of physics which lie so close to us, almost demanding discovery.
The wisest plan for the foundation of such an observatory may be found in the form of a letter in the Smithsonian Report for 1870, already referred to, and it is as an introduction to that letter that the present paper may claim to have any value.
- It is a very noteworthy fact that an astronomer, without quitting his observatory, but by merely submitting his observations to analysis, could have determined exactly the dimensions of the earth, its oblate form, and its distance from sun and moon—data which have been obtained as the fruit of long and arduous voyages in both hemispheres.