SCIENCE NOTES.

Otago Witness, Issue 3101, 20 August 1913, Page 68

SCIENCE NOTES.

—The Time for Rest. — Sir James Crichton-Browno, at the Royal Society of Arts: —“There ought to be before sleep a period of subsidence, a settling down, and no strain or stress on the nerves, not merely in tho ease of children but also in that of grown-up people. There should bo no work done after 7 or 8 o’clock in the evening, but a little recreation or amusement, a little novel-reading, or a cootliing cigar.”

—Motor Spirit from Living Plants. —

Because the supplies of both crude oil and coal are more or loss limited and are impossible of regeneration, a British chemist rises to remark, quite logically, too, that the better way of solving the impending fuel problem is to obtain motor spirit from living plants. Potatoes, beets, and allied vegetables, consisting largely of starch, are capable of fermentation and yield alcohol. It would seem, therefore, remarked the chemist, that the soundest solution of the problem is to be sought along the lines of the production of fuel from some living plant which assimilates carbon by photosynthesis, thereby avoiding the exhaustion of the source of supply. —Queer Facts About Colours. — Experiments have been made to determine what colour in a soldier’s uniform is the least conspicuous to an’ enemy. Of 10 men, two were dressed in light grey uniform. two in dark grey, two in green, two in dark blue, and two in scarlet. All were then ordered to march off while a group of officers remained watching them. Hie first to disappear in the landscape was the light grey, and next, surprising as may seem, the scarlet. 'Then followed the dark grey, while the dark blue and the green remained visible long after all the others had disappeared. Experiments in firing at blue and red target, according to same experiments, proved that blue could be more easily seen at a distance than red. —The tied Radish in Science.—

An alcoholic solution of the skin of a,' red radish serves (says the Scientific American) as m excellent indicator or test for acids and bases. *ln the presence of acids the colourless solution turns pink, while with bases —alkaline solutions —it turns yellow. It. is well known that many plant extracts, such as litmus, and animal products like the cochineal bug, possess this property of developing marked colours with acids and bases, but no other indicator is so simply made. —True Straightness Impossible.—

One of the most difficult problems in practical mechanics is to make a straightedge. How difficult it is may be judged from an incident that occurred in the shop of a celebrated American astronomical instrument maker. A patron asked what would be the price of “ a perfect straightedge of glass 36in long. * It cannot bo made perfect,” said the instrument maker, “but it could probably be made with a limit of error amounting to only a fraction of a wave length of light.’’ “How much would that cost?” “About 40,000 dollars It turned out that the customer wanted the straight-edge for a scraper, and that an error of one sixty-fourth of an inch would not bother him.

—Cheese Matured by Electricity.—

An industrial electrician of Rotterdam is reported to -have discovered a method of giving age to cheese by means of electricity. After a long series of experiments he found (says Grocery) that ho could take an absolutely fresh cheese and give it all the consistency, taste, and appearance of a fine cheese that had been stored away and carefully aged for two years. Ho takes a fresh cheese and subjects :t to an alternating current. At the end of 24 hours of constant alternating electrical currents through this cheese it is said to possess all the properties of a fine two-year-old cheese. This has naturally aroused great interest in Holland, where cheese-making is one of the big industries. It is said the electrician claims he can do many other things with choose by moans of olccti icity, including an apparatus that will enable the iho manufacturer to fo graduate and direct electrical action, of this nature as to give cheese any taste desired and any consistency that may be needed to supply the wants of a fastidious maikct. The Submarine Violin. —

Tho American Navy Department has adopted a “submarine violin” for the transmission of messages between submarine torpedo boats and shore stations or other vessels Exhaustive tests of the apparatus have been made on a submarine at Hampton Roads, Va„ and three sots of tho signal device have been ordered to be placed on as many vessels. Tho mechanism is an adaptation of tho violin. From one side of the submarine project two steel stays. From the end of these is stretched taut a piano wire. Touching the wire is tho roughened rim of a wheel which, when it revolves, sots up vibrations in tho wire. Tho wheel is controlled by a motor inside the hull of (ho submarine, and the motor, in turn, is controlled by a Morse key. When the key is pressed the motor begins to revolve, tho exterior wheel scraping the wire precisely as a bow agitates a violin string. The hull of the submarine acts as a sounding board. The key is used precisely as an ordinary Morse key, and dots and dashes aro hummed on the wire as the key is depressed and released. About eight words per minute is the best speed so far attained.

The receiving apparatus is the ordinary telephone receiver. The end under water may be connected by insulated wires to a fori, shore station, or another vessel. —Deaths by Lightning.— Most people, says Mr Marriott, the secretary of the Royal Meteorological Society, in Knowledge, imagine that the number of persons killed by lightning each year is very great 'lhis impression is largely due' to the lack of reliable information and to the inherent dread of thunderstorms, and is far from being correct. Statistics show that during the 10 years 1901-10 the Registrar-general reported 124 fatal instances of lightning stroke in Kngland and Wales —108 in men, and 16 in women—a yearly average of only 12.4 deaths, or 0.36 per million living. In the 29 years 1852-1880 there were 546 such deaths, the yearly average for that period being 18.8, or 0.88 per annum per million living. The number of those deaths varied widely in different years; three people were killed by lightning m 1863, and 46 in 1872. The annual deathrate from lightning also varies widely in different parts of England. In the north Midlands, from 1552-1880 it was 1.8 annually per million living, in the Metropolitan district only 0.13 (Lawson) —a figure that should be of comfort to anybody who is in London during a thunderstorm. On the Continent much iiigher yearly death-rates are found. In Hungary the annual deathrate from lightning is said to be 16 per million living (Milham); in Styria and Carinthia about 10 per million; <n Prussia 4.4; in Franee and in Sweden 3; in Belgium 2, so far as the imperfect statistics available go (M‘Adie and Henry). In the United States of America the annual deathrate per million is high—about 10 —in consequence of the frequency of thunderstorms on the one hand, and cf the large percentage of the inhabitants engaged in outdoor labour on the other; about 700 or 300 deaths from lightning were estimated to occur in the United States every year by Henry in 1900, in a population of 76,000.000. Many more people are struck by lightning than are killed. For example. Jack records an instance in which a church was struck; 300 people were in it, 100 were injured and mostly made unconscious, 30 had to take to their beds, but only six were killed. Weber gives an account of 92 people struck in Schleswig-Holstein; 10 were killed. 20 paralysed. 55 stupefied, and seven only slightly injured. In 1905 a tent with 250 people in it was struck, and 60 were loft on the ground in various states of insensibility; one was killed outright, another breathed for some minutes before dying, the rest recovered. * As many as 11 and 18 persons have been killed by a single stroke of lightning. Vincent mentions a stroke that threw down 1200, and killed 556 out of a flock of 1800 sheep. Dcchambro believes that children are, perhaps, less liable to be struck than adults; but statements such as these are really not capable of proof or disproof.