SCIENCE NOTES.

Otago Witness, Issue 2785, 31 July 1907, Page 76

SCIENCE NOTES.

{ — A writer in the National Geographical i i Magazine gives an estimate of the extent and probable duration of the coal supply of the Un : ted States. Excluding "Alaska, the amount is estimated at 2,2ooiOOO';million tons. At the rate of consumption f6r"1965', this would last 4000 y^a'rs. If, ' liowever, the rate of increase ofco»snmption j "Tor the last 90 years is maintained, it little more than 100. years; - '.*.•; -t •. -i ' — The amount of electricity for the working of an Atlantic ca>l&- • Js,..surprisingly .small. Generally a, few ceUs^plike those used for electric bells," 3jve emgloyfid. . There may' be from 5 to' loo of.-sheqe. And . a message was sent over, one of the earliest. Atlantio cables^ by means of a battery consisting of a_ silver thimbljjf in 'whjcb~. v was a r Iragment of zinc and a few drobs r 'of sulphuric acid. '''".'/ — The application of instantariecluV photography to lightning flashes has rendered" it possible to say in what direction a' flash i moves. There are alfiaost always Tamiffeations, resembling the rootlets 'Of a-■ plant, from the- -main - and ±bese xaraifi- • cations occur in", the direction towards w.hich j the .discharge: takes place. Tims lighting photographs, reveal the actual ocourrenjeiej iof j the relatively rare phenomenon pf ,~a,-.4}js- ; charge ..passing from ,she" earth, to the clouds. 1 — The basal' mammal^ froml wlijefc"* all j modern beasts (including mareupials I ) 'are , descended, 1 was' possibly a freeihunt'inff crea- ■ ture with 1 five-fi-ngere'e?- hands and' five-toed j prehensile feet,-; a ' lemuf-like animal with ' eome>/v4semblanoe^the modern 1 oppossum. From this" generalised form^of insect-eating, tree-dwelling^ (placenta!; plantigrade' beast, possessing.,' a,' icbnidnuous- dentition of four molars, four pre-molar^, one canine, and four incisor;, (^ee thro pa side ■ of > both jaws, arose, says Sij EL. M. Johnston in th© Tribune, ihe lemur, monkey., ape, and —Dr A. T. Scofield asserts that we are approaching an age when woman will outgrow man. In his opinion she not only has a much better body, but whereas man's brain is old, weary, and incapable of further development, hers is fresh, young, and eager. It is also asserted that girls j mature from one to two years later than' • t formerly, and that their increase in height continues, in some instances, until they are 20. Each new generation is physically an | improvement over the preceding, and incidentally runs the brothers close in the matter of education. — In a communication to the French civil engineers on the artificial dispersion of fog, M. Dibos stated (according to the Engineer) that, quite independently of Sir Oliver Lodge, he began in 1904 his attempts at fog dispersion by electric f waves, clearing spaces 120 m. (equal 131 yards) in diameter by means of a mast 25 m. (equal 82ft) above ground level. He found .that 40 minutes wer© required to clear a space of a little more than the above diameter, and he considers that with a great number of stations — round a harbour, for instance — the air may be kept clear over a large area. The Cie. des Chemins-de-fer dv Nord is much interested in the subject, and has put up stations for various experiments in connection with it. | — 'At a meeting- of the French Academy of Scientists M. Nestor Grehaut contributed some details which are of interest to mine owners and officials as to experiments with the carbonic acid gas, or after-damp, of coal mines, or some emanation from it which -ho terms formene. M. Grehaut has invented a special apparatus for measuring the quantity of this gas in the atmosphere of a. mine at any time, and he has recently been experimenting with it in three different mines of widely different character. In. the wsult he is able to state the proportions of formen© in th© air of the workings as 7 per cent., 4 per cent., and nil. M. Grehaut strongly urges that these proportions should be taken every day in all mines. — Wirel<»ss telegraphy is to play an important part in the linking up of the continent of Africa. In the Cape to Cairo telegraphic system, started by Cecil Rhodes in 1892, the original scheme was to join these extremities of the continent by means | of an overhead wire, and the scheme would probably have been carried out but for the advantage offered by the new system in one portion of the route. The work has proceeded northwards as far a 6 Ujuji, on Lake Tanganyika, and from this point communication with the southern extremity of tho northern wire at Port "Victoria on the Vie- j toria Nyanza will probably be completed j by the wireless system. The country in ' this region is almost entirely unknown, but it is exceedingly broken and rugged, and \ would present enormous difficulties to the establishment and maintenance of an over-"' head wire. The distance in a direct line is about 450 miles, and the spanning of this space by wireless telegraphy should ~ b© comparatively easy and very much 1 cheaper than by the original scheme. | j — A recent article in the Scientific American calls attention to the results of excava- , tions which have been carried on for some i years in the neighbourhood of Naga-ed- ! Der, in Egypt, by Dr J. C Reisner. The , site of the work is supposed to be that of ; the first settlement of man in Egypt, some j 9000 year6*a'go. Th© region, now a desert, ] was then fertile, and^ had an abundant rainfall. Egypt did not then depend on the .Nil© for its fertility. A number of prehistoric mummies have been disinterred, ' preserved in salt, and wrapped in matting ,of halfa. grass. These • are specially , mii teresting as indicating the first stages- inj the art of embalming which afterwards I attained 6uch perfection in Egypt. They [ seem also to indicate that the6e primitive j people held the belief that the body would Ibe wanted again. A careful examination of j these well-preserved skeletons reveals the j important fact that the type has not changed in the long interval of 9000 years. They ar© said to be racially identical with j people now living in th© country. The contents of the intestines are also preserved, ; showing the food they ate and the medicine j they took when they were sick. The diseases of which they died could also some- | t-irrees be diagnosed. Some had perished of kidney disease, others of gall stones, or j diseased boce6. It is thus shown that these i diseases are not the result of modern civilisation. [ — It has been estimated that the whole power of would not be sufficient j to heat the offices and houses of a city as i Jbrge as New York. From time to time ' | suggestions have been made to utilise th© J energy of the tides, but the' great difficulties of such a system are tho amall rise and fall I of the tides -'in.-anosti situations,, <wJbich, of course, means .' a.- -lawi • hea&, and; also th©

intermittent. _ nature of the flow of the Jides. . . This latter drawback means that some - special provision must be made for 'sftjifirig-' T th£ Iwtoeir. The attention of in'y&atorS niis. aw tifceit turned to the problem 4# ■waro-ffl^rsf 'btit- it must "be confessed •that dny power which- we may be able to obtain from- the ocean will be on such a 'small 'scale es <io be almost negligible. Wind-power is a< morfe. reliable- source than i waves or< '.the tides. J3olarlradjatibn has also .been, a -grejs a.&raetiqn< to the inventor. IWis in,. districts* where., there. is little -rainFall „and where there, is small chance of obtaining the; energy, xifi, waterfaDs that there is/ usually" plenty of sunshine! If we '"wort' - ous ' the ; mechanical' equivalent of solar ! "rasiat i fon we ijl fin6! 't&at^' is nearly 3 20,©CT) '^hr.p:" per- "acre 'of ,3pi r face > '"exposed to %H& petfpebdibalap 'rajrs-'6l--the l '3w&."'-'But''fchis ftgupf. applies.- only .to •certtfiS~slatHJtßJes;--and however much this- sonrtie' 'of cteergy might .be utilised it would not (says -Ei^aiieering < Times^ us - sufficient powec - to- heat, the great- rcijie^/jn e©JjJ,. ; cJima.te;s. ,,/,.' — Glass, so< indispea^able,: to. the -chemist anijl . physici^t ( f asj. tl^e, jrtatef^al , for ,experiS* e ?iM. ■ ,fH?P | £ a£gs''a £gs' ' $*$„ RSYf^eless,,. its 'nmnjafitffte.' . 'CnUsT dmong . these," perhaps lJ ,os&ys tflg^9bb^)v"is 7 ifs (l f<lsib ! iKty at'compara'ttvely icJw^^p^fcWre^/^Hentje^ has been k'sougnt^o 'Tor s«srrain purposes vessels and otfher apparatus rtiade of quartz. s^Ebec adviarlag6s*;of'"thi6'--%iaterial are that titi caw bk' healed^.'tot 1800deg F. without it»l coefficient of expansion ,is- v^rybOTPallj &h»t it can be heated red •hot j*no! plung&d , into cold water without cracking, and that ; it permits the passage .of the. ttltra,-violet ra'ye of light. But quartz ,'is^oa.e of( the'-most intractable of substances, and , i ivefe itr'e serious practical difficulties ■^* ov^Voome in utilising it for chemical and 'other 1 apparatus. In Germany small vessels of a somewhat patchy nature have been 'made by heating small clear crystals of quartz and sticking them together, but there is a want of clearness 'in the resulting glass, owing to tlie numerous air- Hufables- It is claimed, however, that a considerable amount of success in making quartz glass has crowned the efforts of experimenters in the Carnegie Geophysical Laboratory,' Washington: The great difficulty was to get rid of the bubbles, and this has been achieved » by first heating th© quartz to a temperature of lOODdeg F., and then, as it gradually cools, applying- a pressure of 4001b ( or 5001b on the quare inch. By this means a solid, clear quartz glass has been obtained. The bubbles are few and small, and do not /interfere with the use of the glass in lenses and other optical instruments. —As illustrative of the tendency of human nature to look with, a pessimistic eye on what have ultimately turned out to be great and beneficent inventions, it is interesting to note that the great chemist, Faraday, gave it as his opinion that it would be impossible to light London streets with gae ; Sir Humphrey Davy (the inventor of the miner's lamp) said that no soientifio man would attempt to store more tihan 20,000 ft of gas in a gas-holder (and there are hundreds now with millions of oubio feet capacity). An eminent thinker lik© Professor Bvmsen (the inventor of the famous burner which bears his .name) said in 1856 that he did not think that electric power could ever be generated with sufficient economy, to drive machinery; it was asserted that it would never be possible to drive ships across the ocean by steam, and that the use of screws on sea-going vessels was ridiculous; and lastly, a celebrated* living electrioian made tihe "avowal before a Parliamentary committee that th© telephone would never be much used in 1 England, because there was not a scarcity of messenger boys in that country! ___^_^^_^_______