132 



KNOWLEDGE 



[July 1. 18'J3. 



warning of their movements when they are several miles 

 distant, by ringing bells, flashing lights, &e. It may also 

 be employed to warn vessels off dangerous points of the 

 coast. Lord Kelvin exhibited illustrations of the mole- 

 cular tactics of crystals, and Prof. H. G. Seeley 

 exhibited fossil skulls from the Karoo rocks, Cape Colony. 



One of the simplest methods by which micro-organisms 

 can be removed from water is by the addition of alum. 

 Experiments carried out at Leeds a few years ago showed 

 that the addition of one-half a grain of alum to a gallon of 

 water reduced the number of microbes by ninety-uiue per 

 cent., and the material has recently been used for purifying 

 water on a large scale in America. It is found that in all 

 cases after agitating water to which a small amount of 

 alum has been added, an absolutely sterile liquid is 

 obtained, though as many as 1200 microbes originally 

 existed in a cubic centimetre (0-06 cubic inches). 



At the Eoyal Society sow'e on May 10th, Prof, ilarshall 

 Ward lectured upon his experiments on the action of light 

 on the spores of bacteria and fungi. He has proved that 

 solar and electric light rapidly kills such spores ; hence 

 "sweetness and light'' were very appropriately coupled 

 together by Matthew Arnold. The destruction of the 

 spores seems to be a direct action of light, and not due to 

 elevation of temperature, or to any indirect poisoning or 

 starving process incident on changes in the food materials. 

 By exposing parts of the same culture of the anthrax 

 bacillus behind screens transmitting blue and violet rays, 

 and behind screens which cut off those rays, it was found 

 that the bactericidal action is almost entirely confined to 

 light of high refrangibility. From observations of plants, 

 it appears that the part of the chlorophyll which absorbs 

 the blue-violet rays is a screen to prevent the destruction 

 of easily oxidizable bodies as they are formed in the chloro- 

 plasts ; indeed. Prof. Ward concludes that the colours of 

 spores, pollen grains, &c., are of the nature of colour- 

 screens, preventing the passage of those light-rays which 

 would destroy reserve substances in the plant by promoting 



their rapid oxidation. 



— *-*-* — 



We recently referred to the scheme now in progress 

 for obtaining motive power from the Niagara Falls. Mr. 

 A. B. H. Thwaite has a plan for the distribution of electric 

 power over a considerable portion of England. His idea 

 is to burn the fuel at the mines, where it costs but little, 

 and then to transmit the power resulting from the 

 combustion of the coal (and gas) by high pressure altei- 

 nating currents. He proposes to use gas engines of not 

 more than 500 horse power to generate the currents. 

 From one station he would supply the centres of industry 

 of Lancashire and the area adjoining the Ship Canal ; from 

 a second, those of Yorkshire ; from a third, those of the 

 Midlands and London. This is a great scheme, but 

 experiments might be made on a small scale in order to 

 test its advantages. 



Mr. Norman Lockyer writes in Xnture of May I8th on 

 " The Early Temple and Pyramid Builders." In his 

 previous articles on Egyptian astronomy he has shown 

 that it is possible to divide Egyptian temples into solar and 

 stellar temples. In the present paper he states that the 

 worship of the bull, Apis, preceded the building of the 

 pyramids. The sun at the vernal equinox 4500 i;.v. was 

 in the constellation Taurus. Biot has shown that the 

 equinox occurred with the sun near the Pleiades in 

 :-!285 li.c. 



If all the rain that falls in a year were spread evenly over 

 the surface upon which it was precipitated, the average 

 depth of water in the area drained by the Thames would 

 be twenty-eight inches. Compare this with the following 

 remarkable diurnal rainfalls described by Mr. Clement L. 

 Wragge, as occurring at Crohamhurst, on the western 

 slope of Mount Blanc, in South-Eastern (Queensland : — For 

 2i hours, ending 9 a.m. February 1st, 10-775 inches ; 

 ditto, February 2nd, 20-056 inches : ditto, February 3rd, 

 35-714 inches ; ditto, February 4th, 10760 inches. The 

 rainfall of February 3rd is certainly one of the highest 

 ever recorded, though it has been exceeded on the Khasi 

 Hills of l^>engal. 



An Indian gazette gives an account of the protective 

 effect of certain colours against the sun's rays. It is urged 

 that no one has ever been a victim to sunstroke or sun 

 fever through a dark source of heat, and it is asserted that 

 the chemical rays do the mischief. A correspondent writes 

 to say that he has had all the linings of his hats and coats 

 made of yellow material, with the satisfactory result that 

 after a trial of five years (often under circumstances of 

 extreme exposure) he has had no return of either fever or 

 sunstroke, to both of which he declares that he was pre- 

 viously a frequent victim. 



^-•-^ 



Extremely useful high-temperature thermometers have 

 been constructed by Messrs. Baly and Chorley by replacing 

 mercury with an alloy of sodium and potassium, which is 

 liquid at ordinary temperatures and remains so through a 

 long range. When a very hard glass is employed to hold 

 the liquid alloy, it becomes possible to determine directly 

 the temperature of any source of heat up to 1150' Fahr. 

 — ►-•-< — 



N((tiiral Science for June gives a translation of a paper 

 by S. Carl Berg, from the Anah's de la Sociedad ( 'ienti/ica 

 Aiyeiitinii of November, 1892, in which the author 

 describes cases of cannibalism among insects, which he 

 has himself observed. The most voracious of the Noctuids, 

 he says, is the caterpillar of Heliothis (irmirjer ; a single 

 one of these consumed in twenty-four hours six or seven 

 other caterpillars. Hitherto cannibalism among crickets 

 has been noticed only among captives, but the author 

 records a ease among locusts in the free state. This was 

 in the drought of 18H3, in the Banda Oriental. He says, 

 " I saw difl'erent attaclcs, in which the conquerors, two or 

 three at a time, got hold of the weaker members of their 

 own kind, throwing them over, and opening the abdomen 

 in order to devour the entrails, these being the softer and 

 more savoury portions, since they contained some of the 

 vegetable food." 



At a recent meeting of the Anthropological Institute, 



Dr. E. B. Tylor exhibited a collection of the stone im-ple- 



mcnts of the Tasmanians, which are unground (iKihvolithic). 



Rough flakes of chert or mudstone, edged by chipping one 



stone with another, and grasped in the hand without any 



handle, they serve the purposes of notching trees for 



cUmbing, cutting up game, and scraping spears and clubs. 



The Tasmanians seem to have kept up this rudimentary 



art until the present century ; and perhaps their state of 



civilization may throw some light on that of the palreolithic 



age in Europe. 



— I • I — 



Professor Dewar, at a recent Royal Institution lecture, 

 showed an air barometer which could measure differences 

 of pressure in a column of air as small as one-millioath of 

 an atmosphere. With a water barometer, which is thirteen 

 times more sensitive than a mercury barometer, such a 

 dift'erence could not even be detected. 



