SCIENCE and INVENTIONS.

New Zealand Herald, Volume LVII, Issue 17597, 9 October 1920, Page 6 (Supplement)

SCIENCE and INVENTIONS .

*— "'• «».'vij iiii'Mii^'-"-"-'!'"-'.-'-.' .. OASLI ,COHSTRTJCTIOK, , Despite the great development of wire- ' .-, less telegraphy, submarine cables are still Toeing construe* ed, and with Ike great in--■-csease. in ijcraamerciat ; and : i journalistic / messages are. Still regarded as a necessary :*■'.-'■■':.'alternative, to'.'-wireless, t and?by, no means :' obsolete or likely to fall into disuse. In : ' ' fact, a new, cable to. the Far East from; Great Britain through the Mediterranean, involving a length of 7000 miles, is being laid section by section as ready, while the " possibility' oi% new .cable from Vance to -fanning Island is now being discussed. 1 ip.2OtJT. - &azo\it> is llia.inamri-igiwn-to- the new; fuel -being'.. tried in Frar-c.j. It is described'' petroleum' residue," which presumably is. the coarser leavings, after the lighter parts have-been /refined away. France produces, and believes in, mazout. a»: : a complete substitote for coal. on '!*%*. main-line : - railways, and' Is being greaW ; ; encouraged by its many advantages. Jtlready -100 engine;} on vne French railway, have" been converted burn the new fuel. . It gives forth no smoke or sparks. _ It requires less labour, for the stoking is done by-turning "a tap. It will get up as much steam in ;fortv minutes as coal will in 180 minutes; it* will run an express train at '60 miles an' hour and drag 60 twentytoa waggons t n ">• long journey, '-,-.;<*._. •;"

K MAS vFfcWEGTIOS'S, I The United States Coast and Geodetic Survey has been', devoting -much • attention J of late to =the-sub«ses ,bf map projections, and has issuedseve&i interesting memoirs relating to projections" which have been little used, together with spectoen. maps. ; The latest.publication ■* this sortvis 'a i new outline : base map of the United States ©at the Lambert zenithal eq,oal-area pro-: jection, scale 1 : 7,500,000, This ie the firsi map on this pjojection erar published by? the survey. Besides . its. useful" pro- ; perty ■of equal: area, the% projection hasJ smaller scale.and direction errors than the j , pr-lyconic projection map whic&has bean! so frequently used sor : census, and -i miscellaneous statistical purposes. ! ' : J

ELECTSIOM, TOKK IHBIISATOE. - ■> There has recently been mtrbduced in German flying circles an instrument that indicates the" difference -in air 'speed between ...the two -wing tips, which art , other way; of . expressing i the , .rapidity of; turns. Two venturi tubes are; -used, ; one over each wing tip. "Each venturi contains three resistance thermometers, one in the throat, on© in r the entrance rsecJaon^vand one in the exit section; I teap'erafawe one in the exit section. The tern. j perature difference '*• between I; that s throat ■. j and the entrance and - exit can;! , tlnis he ; - obtained :y for ' each" venturi. i By* combining two instrument© differentithe difference in temperature between the. two throats can he measured!. This temperature difference will depend on the rate "tk-siingj It is "feat ; tha electrical seo«,aerf,has /fery little lag. /;•/■' ■_ IHfIENSITY OF wmsjESS SIGNALS. A method of measuring and comparing the intensities of - signals ;:recehred-. by-.*; radio station has; f ,Ibeen worked out in France with good results. This method; which can he employed only for undamped waves, ;, essentially consists in comparing ■ the' intensities of reception of the signal ■and of .the BPund : produced by a 'local source,ci ', oseillationsj- .of the. same ire-; queacyT'anS ' form, constituted "by "an. ordinary;- heterodyne, ; . By. modifying the intensity of '-'the action of :the axaafijucy joscllteUtm-generatrag device upon,;j s»y, the. Jaitennai a rough equalisation is feat obtained, afterwards, by manoeuvring 'convenient shunts to the telephone-an ohßolute equalty, of inter.s;ilies is obtained, y .The ration .of intensities is proportional to the ■shunt resistances. Moreover, by inserting & thermo-galvahbmeter in the: antenna, the; absolute '• value of r the • intensity of the aaxfliary signals can ; be. obtained. • The -—«■, error. in ifsbia, practical' use of this.* method tfsisam.j&to;lQ per. cent. \.;. ; "■"".""■''"' ' ' '.'.!'' ■"" ; ■ ■ ■ -t-: