SCIENCE NOTES.

Otago Witness, Issue 3216, 3 November 1915, Page 73

SCIENCE NOTES.

Parrots and Aeroplanes.— In tho course of the present European war it has been noticed that parrots work themselves into a state of intense excitement and screech loudly on the approach of an aeroplane, even before the latter is visible to human eyes. A number of those birds were placed on the Eiffel Tower and other suitable points of observation, in order to test their utility as sentinels. Unfortunately, however, they are unable to distinguish between friendly and hostile aircraft. Seeing Bullets Fly. A writer in the Popular Mechanics Magazine describes seeing a -bullet travelling at tho speed of 2700 ft per second. “ The sun was low over tho eastern hills. Its rays came through a break in the ridge bordering the range, lighting up siosb of tho course of the bullet up to the target 200 yards away, but leaving tho target and) the firing point in deep shadow. The first bullet was seen by someone, and not a man present missed the strange sight later on. Tho appearance was a very brilliant silvery flash, as vivid and quick as a flash of lightning. But two things are necessary to see bullets fly—a dark background, and the sun at right angles to its course.” Sky Periscopes.— In the cities that are liable to be visited by Zeppelin airships the watchers on the lookout for raiding craft have suffered from stiff nocks, and also eye strain from longcontinued gazing at tho heavens to detect hostile aircraft, and to meet this difficulty opticians have devised a special form of sky periscope. This instrument is constructed on the same- general principles as those used by submarines, and the typo that has been so widely adopted for use in tho trenches on land. Tho device is a simple arrangement of mirrors that the watcher can hold in his hand, which enables him to scan the entire vault of the sky while looking down in. a convenient and natural position. It has boon found so convenient that a much better and more constant lookout is maintained. Germany’s Incendiary Ways.— Spraying petrol and hand grenades are some of tho means employed by tho Germans to destroy the fair Belgian villages through which they pass; but the best evidence that they are keen on such destruction, and that it is not tho mere accident of warfare, is tho statement of a foreign correspondent, who describes firebrand diecs, which he asserts are carried by many of the German soldiers,. These consist of small wads, about tho size of threepenny-pieces, and closely resembling charcoal, which are obmposed of a nitre-cellulose material. They are contained in small bags, which, when used, are ignited and thrown through windows of the houses which it is wished to burn. The effect is that each burns violently, and jumps from one place to another much the same as a firecracker, but the combustion causes no noise and leaves no trace. Hysteria, and Its Cure.— An attempt made by Dr Joseph Collins to explain to a patient that her disease was a functional, not an organic one, that it was called hysteria, and that hysteria is not so mysterious a riddle as is currently believed, is of interest because it affords a definition which we think every lay reader will value. It is, said Dr Collins, in reality a splitting off of personality from the composite possession known as individuality or personality, until the individual may seem to have not only a double but a triple or even a quadruple personality. Each of these personalities may be distinct in its delineation, imperative in its activity and determination, and uncompromising. An attempt is made to explain that it is the warring of these errant personalities, plus the fright, that are at the bottom of the excitations and inhibitions that constitute the framework of hysteria, and personality will then dominate the actions of the individual in a harmonious way, or at least with such, harmony that it may bo called normal. As soon as this occurs tho individual is well—that is, he or sho docs not disjilay phenomena that are abnormal. Dissemination of Fungus by Wind.—

Messrs Hcald, Gardner, and Studhalter, in a recent number of the Journal of Agricultural Research, discuss the dissemination of chestnut-blight fungus by wind. This method of dissemination was first suggested by Murrill in 1906, though he probably had only the pycnosporcs in mind. It has not yet, however, been demonstrated that the pycnosporcs can be carried on in this way. The studies of Rankin revealed the fact that under moist conditions the ascospores arc shot forcibly out into the air, where they can be caught up and carried to considerable distances by the wind. Subsequent investigations showed that vast numbers of the ascospores are thus thrown into the air during summer rains. In order to get more definite information regarding this moans of infection, the writers above mentioned carried out observations in a badly diseased chestnut coppice near West Chester, Pa., during the months of August and September. To determine the presence of spores of the chestnut blight in the air at particular times and places a series of exposure plates was. made, while the number of spores present was determined by the aspirator method, and other tests were carried out. The general result of these inquiries is stated as follows: “ jAll of the experiments point to air and wind transport of the ascospores of the chestnut-blight fungus as one of the very important methods of dissemination, and substantiate the conclusions of Rankin and Anderson. _ It can now bo said with absolute certainty that, following each warm rain of any amount, ascospores are carried away from diseased trees in large numbers.

During dry periods wind dissemination of ascospores docs not occur at all or sinks to a very insignificant minimum.” High-speed Stars.— In order to obtain more exact figures m connection with the sun’s motion through space and other similar problems astronomers are measuring the velocity and direction of a great number of stars, which, like the telegraph polos along a railroad track, seem to go rapidly backward as wo move teg-ward. The fact that those stars have motions of their own complicates the case considerably, for the “ fixed stars ” are known to be moving in great streams and change their positions not only in relation to our solar system, but also in relation to each other. The motion of a star naturally resolves it.=elf into two partsr—one measured along the line of sight representing its amount of approach toward us or its retreat, the other measured at right angles to a line drawn from the star to the observer. The first of those motions is measured by a study of changes in the star’s spectrum, the second by comparing its position as measured accurately at dates many years apart. The velocity of a star seems to be a factor of its effective ago Unlike our ordinary human experience, the speed of a star increases with its advancing years, and in the whirl of spheres above us it is the young who cannot keep the pace. The average velocity of stars ranges from between throe and four miles per second for “ young ” stars to above five times as much or “ old ” ones. But notable excep - tions occur. At Mount Wilson Solar Observatory 7 of the Carnegie Institution some stars have been found to move with velocities of _ 90, 100, 115, 155, 210, and even 215 miles per second—the highest speed yet known. These high-velocity stars are sometimes described as runaways, because they seem to be quite beyond the control of the gravitational power of the universe. At their speed the attraction of the entire known stellar system would be wholly insufficient to check the star’s career through space. The astronomer, Simon Newcomb, once calculated that .the maximum velocity attainable by a body starting with velocity zero at an .infinite distance and passing through a stellar system containing one hundred million stars each five tunes as massive as our sun, and distributed throughout a disc-like spheroid of certain extent, cannot exceed 40 kilometres (22 miles) per second. Yet the star “Glioorabridge 1830” has a speed nearly nine times this value, and the massive star Arcturus has a speed probably four times this value. If existing velocities owe their magnitudes to the gravitation of the system the quantity of attracting matter in the whole stellar system would have to bo at least 80 times that assumed by the calculations of Professor Newcomb.