SCIENCE NOTES.

Otago Witness, Issue 2490, 4 December 1901, Page 68

SCIENCE NOTES.

— The investigations oi Bert hzxe made tlear the action of oxygen on organisms Jubjected to feeble acootpbt'jic pressure. His numerous experneeant hsxf- therm that the accidents to -v\iiieh -oae i? exxx^ed m rarefied air can "be aXicScl&d by keeping yearly constant ti>-e qnam-cny ■o? oxyze-E taken in at e-a.ch respiratioD. Accordingly, ance ibis time. aeroiaawß hMrt carried with them ■oxygen, which they bresrse inrougb a Hexible tube fitted vriih a mouthpiece, Cailletet (in a paper r'ad before the Pans '.Academy of Sciences) remarks that this me■thed of taking the oxygen is defective. Ever since birth we have been accustomed to breathe through the res«, and aeronauts 'ttiave difficulty in giving up this habit, and .•breathing -hrough the mouth. Thus the oxygen inspiied through the mouthpiece scarcely fills the mouth, and is ordinarily re-

jected without having penetrated to the 9ung*\ The author presented to ;he academy an apparatus enabling aeronauts to '^arry and have at tlieir disposal large quantities of oxygen stored in small volume, and tc assure the Absorption of the gas ■without taking any particular '.-are. It is. composed (1) of one or several vessels containing liquid oxygen, '2) of a recipient in ■which this is turned into gaseous oxygen, and (3)" of a kind of mask which renders *he respiration of the gas certain. Pure oxygen almost always causes nausea and illness. To avoid this M. Cailletet has placed in the mask a shutter with variable opening, enabling the wearer to mix w ith ,the oxygen a certain volume of air. The aeronaut "regulates ibis opening to that the oxygen iucreases in amount with the height, and, with the object of preventing the condensation of the water vapour contained in the respired gases, he allows it to escape by a flexible lube furnished with a special valve and hidden under Ihe aeronaut's clothes to prevent freezing. ' — The principle of the so-called water curtain which was proposed quite a number of yjears ago for fire protection in theatres, being intended to cut off the auditorium from the stage, has of late been applied in many instances "for ordinary building protection, the arrangement being such as to ttouse water to fall in a sheet — either oil lound- a structure or down one side 01 teveral sides of il^*Jn the case of one large , public building a 7in steel water main ia laid round the top of die structure, upon the broad stone table foimed by the top Df the coping. This pipe is connpeted with farce pumpc in the basement, and, through •erforations properly arranged, insures the introduction of a substantial sheet of water from cornice to pavement, around the whole Dr any imperilled portion ot the building. The arrangement of the system of piping is •aid tc be such as to permit of operating Ip. preecubed sections, and additional reiaye of smaller pipes are placed in position abofe windows and doors m order to complete the curtaining of those points in the knost serviceable manner, -should tli6 curItain. in " the main be broken by wind impinging against the building or through Borne other cause. — Cassier's Magazine, for September.

— The rfact »hat mosquitoes have been prove-d to be probably the sole transmitter? of- malaria and yellow fever has resulted in r, war against the mosquito. It is interesting to 'be assured (writes an American contemporary) that the war against the mosquito has actually borne satisfactory fruit. There have been no deaths from yellow fever in Havana this last summer, and it lias been the first summer for considerably more than 9, ce^tu^ in whicii yeilpjSL ievgt

has not been very prevalent, and in manyCases fatal. How far this result is due to the fact that Havana had been cleaned up ' for the first time in its history and how far to the anti-mosquito crusade is perhaps not easily settled. In Africa and Italy investigations are being pursued by the British and Italian Governments with ardour ; marshes are being drained, stagnant pools filled in, petroleum is being used to destroy the mosquito larvae on ponds and pools, and mosquito nettings have been largely used, and it is said that wherever the mosquito has been destroyed or prevented from biting human beings, malaria and yellow fever have been stamped out. A Brazilian physician, Dr Caldas, has discovered, as he believes, a new serum cure for yellow fever, which is undergoing a searching test by the United States Government. — The latest attribute of the American invasion to present itself ir, London is a street-cleaning scheme from St. Louis, Missouri. The great feature of the invention is that it utilises the power of the pressure on the street hydrants to throw a sheet of water on the pavements with such force that it washes away the accumulated dirt as completely as if the cobbles were scrubbed with a brush in the hands of the most energetic of scavengers. The device consists of a waggon, the body of which is not dissimilar in size and shape to the boiler of a locomotive engine. This tank is divided into two compartments, the larger of which I has a capacity of 6*ogal. Both compart1 meats are air-tight, except for a valve which j connects one with the other. As the water , from the street hydrants is let into the larger compartment, the air is forced from it I into the smaller one, where a pressure of 351b or 401b to the square inch is obtained. This pressure forces the water through the long slit which acts as a nozzle with terrific force. — Sketch. — There are numberless instances reported of pictorial markings on the skin of those who have been killed by lightning. The story generally takes this form : "On the — th inst., during a terrific thunderstorm, John Smith, of X., took refuge under a i tree, which was stiuck by the electric fluid. The poor man was instantly killed, and, ' curiously enough, a perfect picture of the j tree under which he was standing at the j Time of his death was found impressed upon j bis chest." That there are very often ! branched markings on' the skin or a victim Ito lightning there can be no doubt ; indeed, we have a photograph in our possession which exhibits the phenomena most immistakably. The appearance is probably due to the 2ircum=tances that the electrio current breaks up into a branched form on the surface of the skin, and that the intense heat cau=es a coagulation of the blood in the capillaries immediately beneath its path. It can easily be imagined how such an appearance, to credulous observers, would be exaggerated into " a perfect picture of the tree.' 1 etc. — Home paper. | — Geologists and physicists have long speculated on the origin and cause of earthquake-. Sir Humphry Davy suggested the union of certain robust chemical elements as a cause, but more recent views show that the force or energy that wrecks the earth has really a local or surface, rather than af -deep-seated origin. As these phenomena occur near water. thiß latter point has als< to be taken into account in any explanation of their causation. That explanation begins naturally with the primary fact that our earth is a cooling globe. Unlike its pinehed-off satellite the moon, which is a kind of burnt-out cinder, our world exhibits a heated interior, the exact nature therein represented being unknown. Once a blazing orb, the earth has cooled clown surfacewiso, and thus exhibits 0 certain tage in the evolution of planets at large. The remnant of its original heat remains with us, and it is to this heat that we must look as ihe true origin of all volcanic action. If now, we suppose, what aftei all is only a, matter of guesswork, that changes on the earth's crust produce flaws and fissures, we can further imagine how, when water escapes into them and reaches the heated matter of the g T obe, it will be converted into steam. The heated substance will be met with not very far below the crust, so that the point of origin of the earthquake is thus located. When the steam-fiend exerts his enormous powei, he sets "this fine old woild of ours" shivering in earthquake throes. If, contrariwise, there is a vent handy, and tho steam explosion escapes thereby, we get a volcanic eruption. Therefore the whole matter resolves itself into the power of steam generated in the big cosmic boiler which exists below our feet. — London Chronicle. —In the opening lecture of tho se==ion iiwhe Engineering department of the Yorkshire College, Profe«*or Goodman gave a brief description of the new appliances added to the engineering laboratory. Amongst the apparatus described by the professor was a vortox turbine by Messrs G. Gilkes and Co., Kendal, which the lecturer pointed out was fitted with a Kent' venturi water-meter, a most ingenious and wonderfully accurate yet .simple device for measuring the water flowing along a pipe. Other apparatus shown and <-'ealt with included a Campbell oil enghfe, fitted with »onvplete appliances- for measuring ihe. consumption oi oil, po«Pi% inlet md milet tern peratures, and an electrical pyiometci foi measuring the exhaust temperature; a rf>- ; frigeratinq plant, by the Linde British Rcj frigerated Company London: a hydiauhc test pump, by Me.-V. Henry Berry pud Co., of Leeds, the plant eon-isting of" two highpressure, pumps, the one for 'working up°to about two tons per square inch, and the other up to about six tons per square inch ; and a De Laval steam turbine, by Messrs Greenwood and Batley, Leeds. These grai.d j motors, said Professor Goodman, were now ! coming into general u^c. They possessed I great advantages over the ordinary steam engine, and occupied an exceedingly small space. Although this paiticular turbine ran §& 30^000 revolutions per auimt^ jet tlte** A

was no vibration, and it was so perfectly balanced that there was no need to bolt it down. As regarded steam consumption it was far better than the majority tcf simple engines, and would, indeed, compare favourably with high -class compound engines, but in steadiness of running and accuracy of governing it could not be equalled. The lecturer also described a Willans's highppeed compound steam engine ; a M'Phail and Simpson super-heater, an TngersollHargeant two-stage air compressoi, and a Reynolds and Branson special microscope for the examination of the structure of metal. A Whitworth measuring machine had, said the lecturei", been lent to the department by Colonel Harding, and would bo iised chiefly for checking the accuracy of the ordinary measuring appliances. In addition to the appaiatus referred to, a new 50,0001b testing machine had been installed, and various other apparatus for carrying on the work of the department. —Mr John Zeleny, of the Minnesota University, contributes a long article to the Physical Review on the conditions under which light facilitates the discharge of negative electricity. It has been known for over 10 years Jiat if an insulated conducting body is exposed to light there is a tendency for the negative electricity to discharge, the conductor thus becoming positively charged. J. J. Thompson holds that the discharge is due to the ionisation produced at the surface of the body by the rapid absorption of certain of the waves of the impigning light. Assuming this hypothesis the natural path of research is to apportion the relative parts played in the ionisation by the material of the conducting body, the gas theiein occluded and the surface gases. The research described by Mr Zeleny is a contribution towards the solving of the above problems, and the whole matter possesses a very considerable photographic interest, as there can scarcely fail to be some intimate connection between ordinary photographic action and the photoelectric discharge. The main conclusions are as follows: — From a platinum wire the negative electricity is at first discharged more slowly as the temperature h increased, but the rate of discharge reaches a minimum, and then increases as far as the highest temperature employed ; this being about 700deg Centigrade. The rate of discharge is much affected by previous conditions, as on coming down to certain temperatures from a higher one the rate ol discharge is much greater than if a lowei temperature had been used just before. When the discharge is from an iron wire the effect diminishes at first with the temperature, but after reaching a minimum it finally becomes many times the original value at the ordinary temperature.