SCIENCE NOTES.

Otago Witness, Issue 2505, 26 March 1902, Page 64

SCIENCE NOTES.

—An article by Dr Bermbach, in the Eiekilroci.emische Zeittchnft. describes a cascade arrangement of electric furnaces for ii=e in the manufacture of glass which may Jiave a most important effect on that industry. The great fcatuio of tho new method will be that instead of a largo tank holding a great mass of molten glu^s the electric furnace lequirca but a single pet, into which a small stream of glas- is continually flowing," a.= water run 1 - froiii a pipe. Liittle or no timo is lost in <-tc'rting. since the great heat of th' e-leetnc arc piodiu-es nn immediate fu3iou of the powder' d ma terials, and hence the operation rr.iy be started or stopped at any ti'.ic by tb" mere turning on or off the electric current ai d the flow of material.

— Vaccination has one feature in ocmnvn with beer— viz., that it i« irr.no-MJxp to lay down n. satisfactory technical definition <>f cither. The Metropolitan Afylums Coord statistician'- hrvc accustomed il- to take the sear area a a guide to the eft'eacy of pievious varci :ation. To thU j-rrctli-^ tli.'ro are .sundry weighty objectier-. Thoj' are •weight bccai -«■ t'." of an iip-tvuit-.vor.hy indiea r :on of c'i:eti c vaccip - tion i, M"c to fuiL'i^h r!ie pun-vaccination party v, nh an arm to *w sir.mtt v- It niciy -af"ly be .^-.t'-tcd ti '. t i.r t'"-r t''e fi'O noi the depth of tL D .='.ir l.a- ai>y iicc^i-ary relationship to tb.© 6pecific aatiu'e of the jpre-

vious inoculation ; indeed it ih quite possible that extremely well-marked cicatrices are the result of suppuration caused by the intiu.-ion of pyogenic microbe^ at, or subsequent to, the inoculation. Every of experience will confirm the statement that a typical vaccination may "run its course, lea\ing hardly any visible &car, provided that the operation was performed aseptically and remained free from septic disturbance. It i=, moreover, highly probable that the intrusion of pyogcnie organisms in any quantity mitigates, and mr.j oven destroy, tho f-pecific actioa of vaccine lymph, an assumption which would amply suffice to explain the exceptional instances of \aecination or revaccmation not profprting against a subsequpnt attack of smallpox. — Medical Press.

■ — From a paper en the future of the stenm turbine, by Mr W. E. Warrilow, in a leeent issue of the Electrical Review, wme interesting fa< ts about the advantages of the tteam tuibine may be gatheied. Pt^sooing but one rotating pmt and requiring no tpccial foundation, it emboihi'i all that lould be ck rired for coupling to any type cf dynumo for direct or alternating current. The improvements effected in its construction and its employment in a large number of electricity works in this or other countries should indicate that it is destined to fill a prominent place in t lie generating stations of the immediate future Unlike the early undertakings, tho schemes which «re now planned demand units ha\ing capacities running into thousand, of kilowatts, instead of hundreds, so that the cla^s of engine which the turbine represents has every opportunity of appearing to the bost achantage, as far as steam consumption is concerned. Tint question of consumption of gtcam in pounds per kilowatt lia= been a favouiite one with consultants the makei^ of engines being encouraged by the offer of a bonus to reduce it as much ai pos-ible. The guaranteed performance of a reciprocating engine in this respect lias often £;iven it the preference over <-uch an engine a^ the turbine, though no calculation has been made a= to the possibilities of eitliT iMipine to get out of order, or increase its --team consumption with time. An important feature of the steam tin bine, not al\vay<= considered, i, the freedom from great or sudden angular vacations in speed. This defect in reciprocating engines is one which is of constantly increasing importance. With its high rotative Fpeed, and entire absence of reciprocating parts, it is practically impossible for any appreciable variation in speed to occur in the course of a single revolution, the speed changes necessarily extending o\er a number of revolutions, aad being gradual in their nature, while, with ihe u«e of properly jroportionpd governors. e\on tho=e gindual variations in speed may be kept within \rry narrow limit-. A modern turbo plant of 1500 kalowatt capar lty will <-tand on a floor "-pare of 728 square feet, and « ill hiuo n- own condensing plant at that No foundations aie needed for its rpcopiion. and no oil is nere^ary for the lubrication of the rotating parts acted upon hy step iii Lnrci' economics in tmio and ira*orial will b<x offer tod, tho absence of oil in the ssimt -•im p-p<~cial!y enabling the condenard -na'-ri to '->p returned to the boilers. Xo ijl>rat:o]i will t.>ke p'aro while thp plant i-j in motion. The nppoaiancc of the engine room mil a'-o Le greatly enhanced, m that (lie ti.ilo c t;- occupy httlo \\rp.d room, and enn'c \nc ntly will cut off little or i,n li^ht frc)m tlio window 5 . The small icmcnl °p.:re needed i.Ko <io<\s muc !i to decrease t'.p cot cf lunl'lmg- a^ well as tho «tr>am aisd oxh.iu-t pip'nc; for th" turbine. Combined with the=e :t.? the httlo attention rocjuued both for running and maintenance, and the ea-e of manipulation fur paialle-1 running on account of the e\en turning momeat. r -. - -v-

- — "We have beard much lately of the marvels performed by wireless telegraphy ; but we fancy that the last recorded wonder, although not in reality more extraordinary than many of the experiments previously reported, will take firmer hold on the popular imagination. Two Cunard liners, the Lucania and the Campania, were crossing the Atlantic in opposite directions, and each, knowing the date of the other's sailing, could make a calculation as to the hour when they would most nearly meet. That hour came, but the \essels were too far apart (36 mile?) to sight one another Presently, however, the warning bell of the wireless telegraphic apparatus on the Campania tinkled, and a message was spelt out: ''Ar» you there? — Lucania." And then the two vessels, invisible to one another, talked for some hours, each being able to exchange experiences as to the weather, etc. Finally they parted with the message, "Good-bye — pleasant voyage," when they were then no less than 140 miles apart. .Such a conversation carried on between vessels on the broad ocean, separated by such an immense distance, is a great triumph for wireless telegraphy, and breaks the record for communication between ships on the high seas.

—To enumerate the uses to which compressed air is put would be to catalogue nearly everything that steam can do, and tl.en several things more. Thus, compressed air is used to clean impure water ; to dig gold, silver, and iron from mines; to operate sewing machines and jewellers' lathes; to atomise crude petroleum, go as to burn it under steam boilers : to open and close railway gates at level crossings ; to clean grain ; to increase the pressure of natural gas ; to copy letters in a letter press ; to tilt trucks on railway work. Besides this, you can use compressed air to carry letters and packages through tubes underground, and to carry money to cashiers in big commercial houses ; to operate submarine torpedoes, and se*d dynamite shells from great gung on sea and shore ; to make more perfect combustion under steam boilers so as to prevent smoke; to set the brakes on passenger and goods trains ; to operate passenger and luggage lifts, to lift grain from vessels ; and to provide a resilient tyre for bicycle and automobile wheels. What ia more important than this, however, is tl>e fact that in a \ cry few years' time we may have compressed ail" engines running en our principal railways. Somewhat lighter engines would be required for use in railways of the twopenny tube sort. In matters of speed and economy of working the? new engines are said to compare favourably with steam or electric ones. — Express.

— Belleville boilers have been used in the French Navy since 1885, and they meet with great success. This may, perhaps, be accounted for by the close attention that is devoted to them. Frenchmen naturally carry exactness to a degree which we should almost call "finnicky." They treat the joints of a boiler as they would the works of a watch, and as this i& precisely the treatment which water-tube boilers require, excellent results are obtained. It must be romembered, however, that whereas our ships are constantly at sea, French men-of-war are seldom out of harbour for any length of time, and their boilers have not, therefore, been subjected to severe trials on the v<v/ point on winch they have shown themselves to be wcakc-sl, for it is at such times a* when =team is maintained at high pressure. for a considerable time and there is no chance of mending leaky joints or clearing tubes that water-tubo boiler-, give way. The locomotive boiler was easily cleaned, because a mill coul'l get inside and '-crape it, but 111 tube boilers the joints are innumerable, and the tube* measure from lin to 4in in diameter, and are therefore most difficult of access However, economy of space, rapid generation of steam, and a great re-'lm-tion of weight are the undoubted qualities of ll.e newer .sj-tein, =o the necessity of u«ing it in the r-a»e of torpedo destroyers i-j no longer disputed. — Morning Post.

— Whatp\or may bo the ultimate means u=ed for tho production of propulsive power for motors t'irro is no doubt that thr> petrol-\apour-air mixture 1^ the nio-i populai and economical !< rm of cii-ating tLo nc<r--nry fore p. One wou'c' ha\e thought that cleetncity should play ;,n important pan in, motoring, but it must be confessed that mo<-t of the attempts to put a practicableelectric motor on the market have met with comparatively little i-ucces=. The weight of accumulator?, sufficient to give out high and prolonged power seems to be the obstacle in the way of the successful exploitation of electricity for road-traction purposes. On the Cont'iient, automobile experts ha\e been, and aio, busily engaged in the endea■vour to make an eleotiu motor which shall equal, or be superior to, the petrol engine. At the present time, however, the accumulator difficulty seems an almost impofcMble barrier — Sket< h. '