Popular Science Monthly/Volume 46/March 1895/Popular Miscellany
Transportation of Dust in the Air.—In his studies of the atmospheric transportation of matter, Prof. J. A. Uddin finds that the velocities in the atmosphere being so much greater than those obtaining in rivers, lakes, and seas, the distances over which materials may be transported in it will be correspondingly greater, as was shown by the Krakatoa dust, of which the finer particles circled round the earth for months and even years. The greater depth of the aerial ocean renders it but little dependent in its movements on smaller elevations of the land. Few of our mountain ranges are so high as to stand materially in the way. "While the conditions requisite for much aërial erosion are limited to rather small areas of the land of the globe, there can be little doubt that deposition is much more general and widespread; for dust is carried everywhere, and if it be conceded that the atmosphere is never entirely free from dust, it follows that sedimentation occurs wherever and whenever there is a comparative calm. In places in the ocean where sedimentation is known to be very slow, atmospheric dust may be supposed to form an appreciable part of the deposits. The areas of deposition being much greater than the areas of erosion, it is evident that the accumulations of atmospheric sediments, as a rule, are insignificant, only exceptionally exceeding on the land the secular erosion by water, and therefore accumulating only in such exceptional cases. From a dynamical point of view the wind theory would appear to furnish an adequate explanation of the occurrence of the loess in the Mississippi Valley, at least as to most of its phases."
Habits of Polar Bears.—Appropriately to the recent mortal illness of the large polar bear in the London Zoölogical Gardens, a writer in the London Spectator remarks upon the mistake we make in supposing that the denizens of the frozen north necessarily suffer unduly in warmer climates, that "in all stories of arctic travel the extreme of cold appeals so strongly to the imagination that the heat of the nightless summer, in which the Eskimos strip themselves naked in their snow houses, is often forgotten. The good health and long life of the polar bears in this country [England] is less surprising than it at first appears when this extraordinary range of arctic temperature is remembered; moreover, the white bears are absolutely indifferent to fog and wet. Creatures that live and thrive on islands like Nova Zembla, where half their life is spent in fog and darkness, are little troubled by the London fog and damp of Regent's Park. . . . They will plunge and roll in the bath with as much pleasure in pouring rain or when the tank is full of clinking ice as on a hot summer day, and the only weather which seems to cause them discomfort is a hot August afternoon, when they pant and loll out their tongues like Newfoundland dogs." The size of these bears approaches that of the ox or the elephant, rather than that of the true carnivora. In some respects the bears' powers of movement exceed those of cats. They can maintain a gallop at a pace equal to that of a fast horse, leap wide gulfs with ease, swim fast enough to catch a salmon, and dive like a seal or an otter. They heartily enjoy their play, but are dangerous animals. No creatures are more carefully kept at arm's length by their keepers. Men who will rub their hands over a lion's face and eyes or pat the neck of a tiger, shift a bison bull across its stall like a bullock, or handle a python like a length of rope, would think it rash to put hand or limb within reach of these bears. . . . The fierceness of the polar bear is probably due to his enforced carnivorous diet. Every other bear is largely a fruit, vegetable, and ] insect feeder; but in the frozen north the polar bear lives by necessity mainly on fish, carrion, seals, walruses, and birds. Its notion of an 'egg for breakfast' is rather amusing. It will clear an islet of eider-ducks' eggs in a few hours."
Dispersal of Fresh-water Shells.—A recent book by Mr. H. W. Kew deals with the means by which fresh water and land shells are dispersed. The occurrence of these shells is sometimes very puzzling, as when fresh-water shells are found in isolated ponds. It is surprising how varied the means of distribution are. The animals are carried down stream on various floating objects. A case is cited by the author in which a number of anodons were carried away by a whirlwind and fell with the rain. Canon Tristram found the eggs of a mollusk attached to the foot of a passing mallard which he shot in the Sahara a hundred miles from water. A few instances have been noted in which birds on the wing have been shot with bivalves adhering to their toes. Insects also lend their aid, and a water-beetle has twice been captured on the wing with Sphœrium attached to its legs. Another specimen was caught with Ancylus attached to its wing-case, and other aquatic insects have been found with mollsks attached to them. The actual process of transportation of land shells has not often been observed. Some live snails were once found in the stomach of a wild pigeon three days after it had been shot, and an operculated land snail has been found dragged along on the foot of a bumblebee on which it had caught. An isolated dew pond after an existence of ten years will generally yield several species of fresh-water mollusca, and a mediæval fish pond has a considerable fauna. A church or castle built of limestone, but surrounded by non-calcareous desert, is for a large group of land snails the equivalent of an isolated pond; but it is only on very old buildings that one finds colonies of the special limestone species. Mr. Kew also discusses the dispersal of shells by human agency.
Hearing of Infants.—In her Notes on the Development of a Child, issued in the series of University of California Studies, Milicent W. Shinn reports that the infant started violently while nursing, when a paper was torn some eight feet away, on the third or fourth day after birth, and at several times on that and the few following days she started and cried out even in sleep when a paper was rustled sharply as her father sat by the bed. During the first week she did not seem to notice when on his return in the afternoon her father sat close by, reading aloud or talking, but in the second and third weeks she always became restless at this time. The more modulated voices of women who were in the room the rest of the time appeared not to affect her at all. The sensitiveness to sound seemed variable, for on the twenty-third day, when Miss Shinn purposely rustled paper near the baby, it produced no clear reaction, nor did a table call bell struck suddenly and sharply at two feet and even one foot from her head. On the twenty-seventh day she showed no sign of hearing single notes on the piano from the highest to the lowest, yet she started at a hand-clap behind her head. Ten days later, while the baby was lying half asleep on Miss Shinn's lap, the servant brought in a tin bath tub and set it down abruptly so that the handles rattled. The infant started violently with a cry so loud that it brought in her grandfather from two rooms away to see what was wrong. She also put up her lip with the first crying grimace she had ever made, and showed the effect of the fright in a disturbed face for five minutes. Yet throughout the first two months there were also many times when she failed to pay any attention to sounds quite as striking as the few she did notice. The great variation in sensibility was especially noticeable in the second month.
The Tropical Climate.—Respecting the climatology of tropical Africa, E. G. Ravenstein represents that by ascending a mountain we might, even in tropical Africa, enter a region the mean temperature of which coincided with that of England; but if we at the same time considered the annual and daily ranges of temperature, we should find that a tropical climate differed exceedingly from that of the temperate regions. In the latter the annual range was considerable, the daily range small. The character of a tropical climate was the very reverse, for there the difference between the coldest and warmest months of the year was small, while the difference between the temperature of day and night was very great. Nor could we escape these features, even though we ascended the loftiest mountains to be met there. These conditions inevitably led to anæmia and racial degeneracy. Malaria prevailed throughout, even on the plateaus, and some of those explorers who had been loudest in praising the climate as being thoroughly well adapted to European constitutions had fallen victims to its deleterious influences. Europeans might certainly "live" in Africa with occasional holidays in Europe, and they could superintend native labor, but no locality had been discovered as yet where it would be advisable for European agriculturists and colonists to settle down. The districts most favorable to European settlers appeared to him to be some of the hill stations and the steppe-like plateaus which occupied so large an area in eastern Africa, and extended southward into Cape Colony. Speaking of the rainfall, Mr. Ravenstein said that it was sufficient in most parts, but very irregular, so that works of irrigation would be required wherever agriculture on an extensive scale was to be carried on. The humidity, which in combination with great heat produced a climate very trying to the strongest constitutions, was, fortunately, not excessive over a considerable portion of Africa, including all the steppe lands.
Human Characteristics in Apes.—Human characteristics, according to Dr. Lydekker in Knowledge, are most largely developed in the teeth and jaws of the young of the manlike apes and of the gibbons at all ages, and in the skull of the former class. Among other features in which the manlike apes differ from monkeys and resemble men are the absence of dilatable pouches in the cheeks for the storage of food, the loss of the tail, and the flattened instead of laterally compressed form of the breastbone. The gibbons alone retain the naked patches on the buttocks characteristic of the monkeys, but only in a much reduced condition. The gorilla and chimpanzees further differ from the other members of the group, and thereby resemble man alone in the loss of the so-called central bone of the wrist—a bone occupying a nearly central position between the upper and lower rows of small bones of which this joint is composed. What may be the object of the disappearance of this bone it is not easy to say, but the fact that it is wanting in the two genera of apes just mentioned is very significant of their close structural affinity with man. In one respect the manlike apes stand apart from both the human and the monkey type, namely, in the great relative length of the arms as compared with the legs, the disproportion being most strongly marked in the gibbous, which are actually able to walk in the upright posture with their bent knuckles touching the ground. The present distribution of the anthropoid apes clearly points to the existing species being the last survivors of a group which was once widely spread over the Old World, when warmer climatic conditions prevailed over what we now call the temperate regions. Of the four existing genera of manlike apes the chimpanzees (Anthropopithecus) are clearly those which come nearest to man. The chimpanzees and the gorilla alone resemble man in having seventeen vertebrae between the neck and the sacrum, and likewise in the absence of the central bone in the wrist, although they differ in the comparatively unimportant feature of possessing an additional pair of ribs. The gibbons, while they are much differentiated from man, are the only apes which habitually walk in the upright position; and although they frequently aid themselves by applying the hands to the ground, they often while walking clasp them together at the back of the head. In addition to this peculiarity these creatures are remarkable for the extreme agility of their movements and their loud, unearthly cries. The delicacy of their touch is well marked. It is shown by the animals in the London Zoölogical Gardens when they amuse themselves by playing with spiders, which they allow to descend by spinning a thread attached to a finger, then suddenly jerk them back into their hands, and eat them with evident relish.
Exploration of the Upper Air.—Among the ways in which the upper air may be explored for the determination of its physical and dynamical qualities. Prof. M. W. Harrington, chief of the Weather Bureau, mentions investigation of the ray of light that has passed through it by spectroscopic examination and by observations of the twinkling of the stars and of the fluctuations on the margins of the larger celestial bodies when viewed in the telescope. The information obtained in these ways must, however, always be vague, because the total result received by us is the integration of the individual effects at each point of the path, and it is not practicable to separate the sum into its parts; while the knowledge obtained would be otherwise incomplete. Other means of systematic exploration of the free air are by towers, like the Eiffel Tower in Paris, kites, pilot balloons (without aëronauts), and balloons carrying aëronauts. Towers do not reach to the height it is desired to explore. The method by kites has been studied especially by Mr. William A. Eddy, of Bergen Point, N. J. Mr. Eddy uses tailless kites, placing them in tandem, and recommends that they be flown in groups of three. By such means he has attained heights of between four thousand and five thousand feet, and expects to reach fourteen thousand feet without great difficulty. Three tailless kites will fly when any one of the three will not in mild surface winds. They easily right themselves when reversed, and a tandem series of kites tends to prevent the jerking which might put the instruments out of order. The best possible anemometer is a balloon which is immersed in the air and moves freely with it. While such balloons can be employed only for the study of air currents, by a proper selection of places and dates and the assistance temporarily of theodolites and persons capable of working with them they could be made very useful. They would enable us to study the arrangement of air currents about definite meteorological phenomena, such as centers of high or low pressure. A more instructive but more expensive method is that of pilot balloons carrying automatic registering instruments. Balloons sent up by M. Hermite in 1892 carried means for the automatic record of pressure and temperature, but were disabled from registering the temperature by the cold stiffening the ink. They also carried a device for releasing and dropping cards for tracing the course of the balloon, which did not operate very satisfactorily. Much better service than this would be given by systematic work by a meteorologist who would make the ascension himself. Evidence points to the conclusion that the cloud layer and perhaps the upper cloud service is a region of especial activity in meteorological phenomena, but the facts on which such a conclusion could be verified are of such character that they would probably escape any automatic registry. Prof. Harrington furnishes estimates showing that the cost of operating any of these methods could be brought within reasonable limits.
Telpherage Lines.—The telpherage method of transportation is much better known in Spain, Italy, and the British colonies than in England and the United States. Its history may be hypothetically traced as an evolution from the single-rope bridges of the Himalayas and Thibet—cables made of twisted birch twigs on which the passenger crosses seated in a hoop, which he hitches forward while he holds the rope above with his hands. The next development is to fasten a cord to the hoop by which it is drawn to either side. A similar rough form of transport, except that buckets and wheels were used instead of the hoop, was employed for many years in the lead mines of the Peak of Derbyshire. A great impulse was given to the method by the invention of twisted steel cables, which made the lines stronger and more lasting. More than two thousand miles of telpher line are now in working order in Spain, Italy, South America, India, Cape Colony, China, and Japan. A line at Hong Kong, rising ten hundred and ninety feet in two miles, is used for the transportation of the European workmen at the port up the mountain at night, in order that they may sleep in purer air. It is led straight up the mountain side on high steel trestles, and carries, in little back-to-back cars, three persons on each side. At Table Mountain, Cape Colony, the suspending wire is carried in a single span fourteen hundred and seventy feet to the edge of the cliff, and thence in another span fourteen hundred feet to the top of the mountain. At the Rock of Gibraltar the wire runs, after a first leap of eleven hundred feet, straight to the summit on a series of lofty trestles in an ascent of one foot to every foot and a half. At Bilbao, in Spain, nine lines run from the station at the foot of the mountain to the mines at different levels along the summit, and carry on an average twenty-three hundred tons of ore a day, none of which touches the level of the ground through its journey of five miles. It is calculated that one hundred thousand tons of ore can be carried on each of these cables before it becomes unfit for service. In crossing wide ravines or rivers, where one bank is lower than another, the gravity system is employed, the descending load being used to haul up the ascending car. In the Italian Alps a span of fifteen hundred yards is crossed without a support, and the method is soon to be applied to distances of two thousand yards.
Effects of Freezing on Plants.—The study of the effects of freezing upon plants has made less advance than that upon the best temperature to promote their growth. Some observations oil the subject have been published by Signor Sebastiano Cavallero in Italian journals. All plants, aside from a few tropical species, resist temperatures ranging from the freezing point to —110º F. Beyond these extremes their resistance varies with the species. It is well known, moreover, that woody plants and many herbaceous plants freeze and thaw without being visibly injured. Forests of larches, birches, and pines grow in Siberia as high as the seventy-second degree of latitude, where the temperature often falls below 50 F. Several kinds of pines, willows, junipers, and alders grow along the Mackenzie River in latitude 69º. Mr. C. Gibbs, of Abbottsford, found in 1882 that the apple crop of twelve Russian villages, on the western bank of the Volga and south of Kazan, was valued at fifty thousand dollars a year. The fruits are sold in the markets of Nijni-Novgorod and Kazan. The region is subject to temperatures, as was experienced in 1887, of —40º. So apples grow well in the northern United States, where such temperatures are not unusual. The greatest resistance to cold is offered by seeds. Next in power of endurance are the cryptogams—mosses, algæ, and fungi. Except the hardy trees and shrubs of the temperate and frigid zones, and the hardy perennial herbs, most of the phanerogams perish between the freezing point and —20º. The most obvious effects of freezing upon plants are noticed in herbs and bulbs, which are stiffened and assume a shining appearance, often oleaginous and transparent. The effects of frost on trees are not visible unless the temperature descends to near zero, when they are often cracked to the center. Internally the sap is congealed in the tissues. Until recently the death of the plant was attributed to the frosts dilating the cells and distending the tissues. During the winters of 1887-'88 and 1888-'89 Signer Cavallero found, with a microscope magnifying three hundred times, that the tissues of a frozen vine were not torn and that the cells were not frozen. The crystals of ice, on the other hand, were formed only in the intercellular spaces. These facts do not afford indications of the vital condition of the plants, for they are observed in those that resist the cold as well as in those that succumb to it. The chemical modifications are of much greater importance, for they determine or attend the death of the frozen plant. Signor Cavallero's data agree with those of MM. Sachs and Jumelle, and point to the thawing as the principal factor of the death, for frozen plants may be made to live by taking precautions to thaw them slowly. In fact, while the plant is thawing rapidly, the water leaves most of the tissues before it is reabsorbed by them; and the abnormal concentration of the tissues provokes death. But when the thawing process is slow, most of the water returns to the cells and restores the equilibrium which primarily existed in them.
Sounds made by Ants.—That ants are capable of producing sounds intelligible to their fellows and even audible to our ears seems to be proved by the experiments of Sir John Lubbock, Landois, Robert Wroughton of Bombay, C. Janet, Forel, E. Warsmann, and others. It also seems to be determined that the sounds are produced by the rubbing together of superficial portions of the body. A simple yet ingenious contrivance is described for enabling an observer to hear and study these sounds. A glass tunnel is set, small end down, in the middle of a square of window glass of five or six inches side, fitting closely enough to prevent the insects crawling out under it. A bunch of ants about as large as a chestnut and free from any foreign substance is dropped through the tunnel, and that is lifted up at once. While the ants are still confused, and before any of them can reach the edge of the glass, it is covered with another square like it, which has been surrounded, a short distance from its edge, by a pad of putty. This confines the ants and prevents their being crushed. The two plates of glass are pressed together to within about the thickness of an ant's body, but closer on one side than on the other, so as to hold some tight and leave others free to take such positions as please them. On applying this box of ants to the ear as one would a watch, a regular buzzing may be heard like that of water boiling in an open vessel, and with it some very clear stridulations. The ants may be kept alive several hours and even days in this prison if it is not air-tight; and whenever the ants are excited the stridulations may be heard very numerous and intense. The stridulations are supposed to be produced by rubbing the rough scaly surface of the chitinous covering, which is described as looking, when seen in one direction under the microscope, like the teeth of a saw.
Ancient Use of Copper.—The range of metals and alloys at the disposition of the craftsman is really very wide, but he, nevertheless, Prof. Roberts-Austen says, restricts his efforts within narrow limits, and employs but few materials. The pure metals and fine wrought-iron work are seldom used, and have hardly any applications in art industries except when in union with other metals. The two series of alloys which have prominence in the history of art metal work are those of copper and tin, the bronzes, and the copper-zinc series—the brasses. Next in importance should come the lead-tin alloys—the pewters. Of the alloys of the precious metals, the gold-copper, the gold-silver, and the silver-copper are the most important. Taking the bronzes first, the important question at once suggests itself whether copper was employed before the general adoption of the alloy of copper and tin in industrial art. Berthelot has given us the analysis of a little Chaldean statuette of a god, now in the Louvre, which is considered to date from 4000 b. c., and it proved to be of metallic copper. There is also an analysis by Berthelot of the scepter of King Pepi I of the sixth Egyptian dynasty. This scepter, believed to be thirty-five hundred or four thousand years old, now in the British Museum, is of pure copper. From the anthropological point of view copper plays an essentially different part in prehistoric culture now from what was assigned to it a short time ago. Whereas it had been assumed that copper periods existed in Europe only in a few localities, finds of it have recently increased to such an extent that the assumption of a special copper age, which was prior to the bronze age and contemporary with the later stone age, seems to archaeologists now inevitable. Many of the objects found in Schliemann's first prehistoric city, Ilios, were of nearly pure copper. Other articles in the third city were of bronze. Our knowledge as to the first appearance of bronze has recently received new evidence in a rod found by Dr. W. Flinders Petrie at Meydum, of the fourth Egyptian dynasty, about 3700 b. c., which proves to be a bronze having about the ratio of nine parts of copper to one of tin, characteristic of far later and even of modern bronzes. Two works in the South Kensington Museum, one Etruscan and the other Greek, afford clear evidence of the introduction of tin into the art of those nations in the fifth century before Christ. The fact that the presence of lead in bronze enabled it to be more easily fused and also to assume a beautiful velvety-brown patina was, in the opinion of the author, recognized far earlier than has been supposed. Lead occurs in the analysis of a fragment of Greek bronze of a date about 450 b. c. The use of zinc is indicated in the descriptions in detail by Pliny of the various shades of color presented by bronze. The use of brass, which was common enough in Roman times, does not seem to have prevailed in England until William Austen, in 1460, made of it the magnificent monument of Richard Beauchamp, Earl of Warwick.
Preservation of Virginian Antiquities.—An Association for the Preservation of Virginian Antiquities was formed in 1888, at the suggestion of ladies of Williamsburg, and chose the wife of Governor Fitzhugh Lee as its first president. Mrs. Lee was succeeded at the expiration of Governor Lee's term by Mrs. Joseph Bryan, who is now president. The first work of the society was to secure the "old Powder Horn," or powder magazine, in Williamsburg, which was built in 1714, and was the object of historical disputes between Governor Lord Dunmore and the Commons, among whom Patrick Henry was prominent. This building was in a state of decay. It has been repaired and restored to its old proportions and appearance. Next the society saved the picturesque home of Martha Washington in Fredericksburg from being carried off to the Chicago Exhibition by purchasing it. It has been made to look, within and without, as much as possible as it did when Martha Washington lived in it. The house is to be used as a museum for colonial and Revolutionary relics. The churchyard at Jamestown, with its ruin and twenty acres of land adjoining it, have been presented to the association by the owner, Edward F. Burney, and will be preserved and kept in order. The restoration of the Old Brick Church (St. Luke's) in Smithfield, Va., which was built in 1632, is contemplated as the next work of the association; and it is negotiating for the possession of the old lighthouse at Cape Henry, which was used for about one hundred years, but was abandoned about fourteen years ago for a new and more modern structure.
Discovery of a "Missing Link."—Dr. D. G. Brinton communicates to Science an account of the discovery in the early Pleistocene strata of Java of three fragments of three skeletons, that introduce us to a new species, a new genus, and a new family of the order of Primates, Pithecanthropus erectus, standing between the apes and man—in other words, apparently supplying the "missing link" which has been so long and so anxiously waited for. The material, Dr. Brinton says, "is sufficient for a close osteological comparison. The cubical capacity of the skull is about two thirds that of the human average. It is distinctly dolicocephalic, about seventy degrees—and its norma verticalis astonishingly like that of the famous Neanderthal skull. The dental apparatus is still of the simian type, but less markedly so than in other apes. The femora are singularly human. They prove beyond doubt that this creature walked constantly on two legs, and when erect was quite equal in height to the average human male. Of the various differences which separate it from the highest apes and the lowest man it may be said that they bring it closer to the latter than to the former. One of the bearings of this discovery is upon the original birthplace of the human race. The author (Eugene Dubois, of the Dutch army) believes that the steps in the immediate genealogy of our species were these: Prothylobates; Anthropopithecus sivalensis; Pithecanthropus erectus; and Homo sapiens. This series takes us to the Indian faunal province and to the southern aspects of the great Himalayan chain, as the region somewhere in which our specific division of the great organic chain first came into being."
The Work of the Naturalist.—With its second number, January 11th, Science gets into good working order, and gives a budget of excellent scientific papers from first hands. Among them is a clear summary of the proceedings of the Baltimore meeting of the American Society of Naturalists during the last Christmas vacation. At this meeting the influence of environment upon the successive steps of development, and as a cause of variation, was discussed with considerable freedom. Prof. Charles S. Minot, of Harvard, spoke on the work of the naturalist in the world, defining his object to be to discover and publish the truth about Nature. First and foremost of the conditions of success is truth. The naturalist's first business is to get at the truth, in the way of which stand as the most prominent obstacles the limitations of his own abilities and the limitations of accessories for carrying on his work. The naturalist must observe, experiment, and reason, and his training must necessarily be along these lines. The great work of the future is to be done by experimenters. Again, the reasoning faculty is one of our weakest points. The naturalist must learn to distinguish carefully between discussion and controversy, and while being led and taught to indulge freely in the former with all the intelligence at his command, he must also be taught to avoid the latter. The naturalist is exposed to many evils like this matter of controversy, which tend to cause him to depart from his proper mission of getting at the truth. He is especially liable to be led away by impatience to get results. Preliminary communications are a very great as well as a very prevalent evil. The greed for priority leads many even fine workers far astray. The tendency to speculate is a third evil, and a fourth is the disposition to accept too readily simple and well-finished conceptions. It is the function of original memoirs to assimilate crude facts and render them digestible. Details not bearing directly on the subject should be carefully excluded. Most original papers could be "boiled down" to one half and some even to one tenth of the amount that is really published. The effect of the work of the naturalist upon his own character is best shown by his optimism. One drawback in the naturalist's life is his comparative loneliness and isolation. Seldom has he in his own neighborhood another interested in the same particular line as himself. Reunions of naturalist societies counteract this to a considerable extent, but there is need of even greater affiliation. Naturalists should exercise influence in teaching men competence. The solution of our present political troubles lies not so much in restricting the right to vote as it does in restricting the right to be a candidate. We, as naturalists and as citizens, should uphold competence. The naturalist should see that the schools educate, with science in its proper place.
The Senses of Plants.—The conclusion is reached by J. C. Arthur in a president's address before the Indiana Academy of Science on The Special Senses of Plants, that plants seem to react sensitively to gravity, light, moisture, heat, and contact. Each is a special kind of sensitiveness having its own method of reaction. Two or more kinds of sensitiveness may reside in the same organ, when its position will be a resultant of the several forces. There are consequently no exclusive organs of sense, although there is more or less localization in certain parts, and there are no nerves, although the motor impulse may be transmitted some distance, even so far as twenty inches or more in very vigorous Sensitive Plants—that is, in Mimosa. There are also no muscles in plants, although they execute movements of very considerable amplitude. The real mechanism by which the movements are accomplished is not well understood. There is agreement, however, in assuming it to be due to the movement of water. All the senses, except that of contact, have for their end the adjustment of the plant as a whole, and of each of its organs, in a suitable position for heat development. The contact sense has been more variably developed, aiding the plant to climb, to catch insects for food, and, if we are to accept Darwin's suggestion, enabling the Sensitive Plant in particular to escape the injury of hailstones. All the movements are very slow, except a few like insect-catching and hail-avoiding movements, and their wonderful diversity and extent are realized only by instituting carefully devised experiments and the use of delicate instruments. It is to be noted that the same organ always responds to the same stimulus with the same corresponding movement. There is no opportunity for choice, no volition, and consequently no mental activity, no psychic life of even the most humble and rudimentary nature.
Characteristics of Maps.—Maps, said Dr. R. H. Mill, in a lecture on Holiday Geography at the Royal Geographical Society's rooms, may be viewed as a kind of shorthand, and are easier to read than books. Far more information is given in a map than could be written or printed upon a piece of paper of equal size, and a map could point out to several persons coming from different directions the way to a certain place, since it does not introduce the confusing notices of right and left, as verbal instructions do. In Aberdeen the confusion is avoided, because there a man is told to go north or south instead of to the right or left; and it is even said that in some places in Scotland the position of the dishes on the table is regulated by the same principle. The value of maps depends on their purpose and their accuracy. A map that had been taken from a tramp, exhibited to the audience, though worthless for the measurement of distances, was very valuable to the beggar, since all the houses were marked upon it, and the character of their inhabitants, together with the presence of dogs, were indicated by peculiar signs. In a number of old pictorial maps various strange animals were seen disporting themselves. Such maps, like a bird's-eye or "balloon" map, give a very good idea of the locality, but in them the scale is continually changing, so that they do not fulfill the true function of a map, to enable measurements to be made. In plans, as distinguished from maps proper, the ground is treated as if level, and no notice is taken of the curvature of the earth. A map proper makes allowance for mountains and hills and the earth's curvature. The speaker referred to the pleasure a traveler might obtain from marking out his journey day by day on a map. Nothing can more convince a man how little he knows of his own country than a map on which are indicated all the railways he has traversed. He would find the places he had seen much less numerous than those he had not.