SCIENCE NOTES.

New Zealand Mail, Issue 1687, 29 June 1904, Page 18

SCIENCE NOTES.

COMETS AND THEIR TAILS.

An important and interesting essay "by Prof. Barnard has just reached this country (as a reprint from “Popular Astronomy”) entitled “Some Peculiarities of Comets’ Tails and their Probable Explanation,” in which its gifted author deals with the phenomena exhibited by Swift’s Comet, 1892, Brooks’s Comet, 1893, and Borelly’s Comet, 1903, as depicted in the photographs taken of these bodies. Beginning with Swift’s Comet, we learn that an unusually large portion of the cometary matter was separated apparently by the disruptive and repellent force of the sun, presenting the.appearance of a secondary comet with several tails of its own. In this case the repellent action of the sun would fairly well account for the phenonmenon observed. When,- however, we come to

BROOKS'S COMET,

the phenomena were unique, and are only explicable on the assumption that they had their origin in some outside cause, inherent neither in the comet nor in the sun. “The tail,” says Prof. Barnard, "which one day was in a nor- . mai condition, was in the next broken V and disturbed as if it had encountered some resisting medium in its fight through space. The disturbance seemed to coon© from; the direction towards which the comet was moving. On the suceeeding morning it was badly broken, and V hung in cloudlike masses, some of which were entirely torn off from the tail, and appeared to be drifting away in space. On another occasion the tail was concave towards the direction of motion, and had the appearance of beating against a

CURRENT OF RESISTANCE. . It was disjointed in places, and near the •nd was abruptly bent at nearly a right angle, as if at that point it had encountered a stronger current of resistance. If on© examines these pictures there seems no escape from the conclusion that this comet’s tail did actually encounter some resisting or disturbing medium about October 21, 1893, and for several days subsequent to this date. ? Whether this was a swarm of meteors, such as we know exist in space near the sun, or some sorb of resisting matter of which we as yet know nothing, is a subject for time to.settle.” Finally, in the base of Borelly’s Comet and the separation of a section of .its tail from its head on July 24 last year, Prof. Barnard explains this on the assupmption that there a slight but sudden change in the direction of the emission of matter from the comet. The first tail would then separate entirely from the comet, and a new tail would begin in a new direction, while the section would drift out and he dissipated into space.—“F.R.A.S.” in “English Mechanic.” THE HOLE LEFT BY THE MOON. . People have a dim recollection of having read somewhere that the moon is ail offshoot of the earth, but the statement that the moon is the earth’s child' assumes a vivid interest when one is told that the huge * depression in our globe, which is. now filled with the waters .of the Pacific Ocean, may be the very scar that*was left when the lunar body was violently separated from that of its parent. ' It was, hazards Professor Gr. P. Serviss, a birth on a most stupendous scale, the memory of which, if there could have been human beings then in , - existence to behold the cataclysm, would have been handed down in strange tradition through all subsequent time. But this birth of the moon probably ante-dat-ed the appearance of living creatures on the earth, because the globe at that time must have been still in a molten condition, although it may have been al- - ready stiffening in consequence of cooling, so tnat when the moon was flung off a deep scar was left-, a huge hole in the surface, which slowly filled up again as the hot rock, moving like softened wax, gradually flowed into the depression. But the latter, if the suggestion that the Pacific Ocean basin represents the place where the moon was born is to be taken seriously, was never entirety filled. The molten mass hardened into solid rock before the cavity was fully concealed!—“Science Siftings.” APPARENT INTELLIGENCE OF ANIMALS. Mr J. Burroughs, in the ‘‘Century,” protests against attributing human . powers-of thought and prescience to ani- . mals. Admitting that the example of parents stiniulates the imitative instincts of their offspring, the author in- ' sists that teaching—in the sense of imparting true knowledge—is conspicuous by its absence in all animals. Such communications as do pass between animals (and means of communication •undoubtedly exist) relate only to the future, and simply come under the denomination of feeling or emotion, in contradistinction to knowledge. As regards the means by which large bodies of animals, such as flocks of starlings or : pewits, herds of. deer or antelope, or shoals of herring or mullet, act,in com- ; . plete unison, as if acting under the influence a leader or a code of instructitf.ii, the author : is inclined to attributes the phenomenon to something analogous to telepathy in mankind. . “There is nothing,” he writes, “in this state .of things analogues to a military organisation. The relation among the

members of the flock is rather that of creatures sharing spontaneously the same subconscious or psychic state, and acted upon by the same hidden influence, in a way and to a degree that never occur among men.”

THE INVENTION OF “PERFORATION.”

It is said that the knighthood which was conferred on Sir Henry Bessemer in 1878, when he was 60 years old, was a tardy reward for a service rendered the joritish Government about the time of his attaining his majority. ,The history of this, as told by' James Dredge, is that at the time when, in his early years, Bessemer came into contact with some of the officials of Somerset House, the seat of the Inland Revenue Department, it was notorious that frauds on the Go--yemment were perpetrated to an alarming extent by the repeated use of stamps affixed to deeds. It was estimated that an annual loss of £IOO,OOO was sustained from this cause, and to devise a means for entirely putting a stop to this occupied Bessemer’s attention. It is almost superfluous to say that he arrived at a solution by the simplest means, that of perforating the Government stamps with dates. Now that this evident method has found a hundred uses throughout the civilised world to safeguard stamps or cheeks, and to divide postage stamps, being among the most common, it is a little difficult to realise the importance of this invention. SMOKE SLOWLY. From the medical profession comes another warning to smokers. If you wish to avoid tobacco cancer don’t smoke fast. After careful observation it has been practically determined that this form of cancer is caused by the irritation resulting from the heat of the cigar or pipe. Men who smoke longstemmed pipes, it is said, • do not have cancer, no matter how much they smoke, while those who indulge in cigars or short-stemmed pipe® are afflicted by these malignant growths. Tobacco cancer eaused the death of General Grant. He was an inveterate smoker and he smoked very fast. At the battle of Shiloh he is said to have consumed 50 cigars. PHOTOGRAPHIC) EFFECT-OF RADIUM RAYS. It' is interesting to note how pictures of the portions in relief on coins, medals, etc., can be obtained by means of radium rays. The coin or other object is placed directly in contact with a photographic plate which is enclosed in an envelope opaque to light. A few milligrams of radium bromide, contained in the usual mica-covered box, are placed some distance above the plate, and the whole left for several days. After development it is found that a clearly defined picture is obtained of the portions in relief on the under sides of the coins. Pictures have thus been obtained of the portions in relief on silver coins (halfcrown, sixpence, also of a name engraved on a mother-of-pearl seal. Ten days was tlie time of exposure when ten milligrams of radium bromide were placed six inches above the plate, and the coin was a threepenny bit . Ten days also in tlie case of a halfcrown when five milligrams were placed lynches above the plate. THE FOOD VALUE OF EGGS. Eggs (says “Health”) are a very nourishing food; and represent two important elements, fats and proteids, in an easily assimilated form. A single egg weighs about one and one-half ounces, of which one ounce is white, or pure albumin. and one-half ounce yolk. The nutritive value of .the yolk is greater than that of the white, though its bulk and weight are smaller. Its solid constituents' are about one-half of its fat. Fresh eggs. - properly prepared, are readily digestible. The best mode of preparation is whipped raw, or cooked for 20 or 30 minutes at a temperature of about 160 deg. (curdled). The yolks are more easily digested when boiled hard, and the whites are also easily digested when hard boiled, providing care is used to reduce the coagulated white to minute particles which may readily be dissolved by the gastric juice. A single egg is equal in value to a dozen oysters. ‘ FUIMELEB9 EXPLOSIVE FOR MINING. A fumeless explosive for mining has long been wanted, as in underground mining cue fumes of blasting compounds are dangerous, and entail loss of time. Experiments with a new explosive called “Herculite,” made at Fishponds, near Bristol, seem to indicate that the need has been met. A mass of over 30 tons of rock was displaced by a single “shot” of 12oz, and no fume was detected. It is claimed" for the new invention that it is both more powerful and much cheaper than the hydraulic and nitro-glycerine compounds in use. CHANGES IN WATER LEVEL. The recent news of the sinking of the level, of the Sea of Azof, threatening some of the commercial interests of Russia, is supplemented (by a report that the Aral Sea and Lake Balkash, the first 1000 and the second nearly 2000 miles east of Azof, are rising, although up to 1891 the Aral ’Sea had for many years been sinking. Some geologists think these changes are due to slow upheavals and subsidences of the earth’s crust.