WIRELESS NEWS.

Press, Volume LIX, Issue 17691, 17 February 1923, Page 11

WIRELESS NEWS.

SLATE FOR PANELS. AUSTRALIAN COMMERCIAL SCHEME. (ancuLLT -warms *oa "ssx musss.") (By Electra.) x Slate no doubt has high insulating properties, but its one drawback is its tendency to condense moisture on its surface, thereby causing creeping of a.i electric charge. This can be 6een by placing the warm hand on a pi.ce of slate, and even when standing on a slate pavement moisture will soon appear, even through the best soles. Before warm weather in the slate' quarry-1 ing districts the surface of slate slabs wid have beads of moisture on them for several days, due to the condensing of tho moist air on the surface. This does not happen in the case of metallic surfaces, the suggestion being that tho latter conducts the heat away, whereas slato is practically a non-couductor of heat. Apart from this drawback slate is a non-conductor of electricity. It will cleave in more than one direction, but the most favourable is that paraJel to its surface. To obviate the ■ suriaee creeping oi an electrical ciiargc ! 1 suggest shellacking the surlace. 81k-1-' lao adheres well, and gives it an orna- : mental appearance. Tne slate top oi a high-tension battery treated in this manner will give very satisfactory re- ! suits. i As to the method of working elate, 1 i suggest a hack-saw rather than a carpenter's saw. To piano tho surface ot a slate slab, a chisel 1£ inches wide, j with a fine, edge, 6hould be made from : an old iile; the edge should b* well j hardened. The surface can be smooth- j ed iyy rubbing it crosswise and length- | wise with this chisel, hold.ng it s ant- | wise, using a straight-edge to test for j accuracy. AVhen tiling the sides and ends a slight chamfer should be made with a file on the off-side to avoid fraying when drawing the file. Both surfaces, sides, and ends can then be polished with very fine emery or gb.sspaper, and finally shellacked. No trouble should be experienced in obtaining a good smooth surfaca, but the experimenter will find it a messy business. If slate i 9 split into thinner sheets, this should be done from, either end, and not from the sicles. Slate can be bored very easily with an. ordinary breast drill. Testing 'Phones. The following method of testing earphones is less difficult, and perhaps more efficient than testing by the "weak ( battery," tongue and lips, or sixpence and penny method. The two leads from the 'phones are connected to the two terminals of an ordinary electric bell. No battery whatever is nut in circuit. The armature is pressed forward to the magnets and then quickly released. It will vibrate several times before corning to rest. A similar vibration will take) place, and will be plainly heard in the , phones. The explanation of the action I is that there is a small amount of nag- ' netism in the magnet of the boll when ; it is-not connected to tho battery which • usually works it. When you cauee the j armature of the bell to vibrate the magnetism is disturbed, and svts up currents in the coils of the magnet core. These currents work the diaphragms of your phones, and you hear a sound agreeing with the vibration of the armature of the bell. t Direct "Wireless Communication Between Britain and Australia. Tho Commonwealth Government has entered into an agreement with Amal- ' gamated Wireless (Australasia), Ltd.. 1 for.the establishment of direct wireiess • communication with Great Britain, and • the erection and operation of a powerful , station in Canada. The agivcuuvnt stipulates that the- capital of the company shall be increased to £1,000,000 in £1 shares, and that 500,001 of these shares shall be taken up by the Commonwealth Government, with ra-yvision for the retention by the Government of a majority of the shares should the capital of the company at any time be increased. TJnder the terms of the agreement the company will proceed forthwith with the erection of apparatus for wireless communication, and the transmission of energy, and shall undertake the following programme: Construct, maintain, and operate in Australia the necessary stations and equipment for direct commercial wireless service between Australia and the United Kingdom. Provide and operate a system of feeder stations for wireless connexion between the main high-power stations and the capital cities of all the States. Equip and organise the feeder stations so as to provide communication with merchant ships around the coast of Australia. Arrange that the rates to be charged for messages between Australia and the United Kingdom transmitted or received by the company shall not excted the following:—Full rate messages, 29 per word; deferred messag-'s, Is per word; week-end messages, 6d (minimum 103 per message); Government messages, Is per word; Press messages, 5d per word; deferred Press messages, 3d per word. Arrange for the operation of suitable rorresnending stations in the United Kingdom. Provide the main trunk stations in Australia and the United K ngdom within two years. Arrange within two years for the erection and operation of a station in Canada capable of commercial communication with the highpower station in Australia, and jso equipped as to afford facilities for distributing traffic throughout North America. In regard to the radio stations already operating in Australia, the company has taken over all -tations excepting'those win illy controlled by the Department of Defence, and wdl operate and reorganise the systrni in ordjr to furnish a at least equivalent to that which was supplied before this agreement. The sites, buildings, masts, and oilier assets concerned will be t;:k"n over at a valuation made by a '•omimtte-?, inclvding two representatives of the <omi panv and two of the Government, with an independent chairman, or by arbitration. Sadio Licenses. The long sought for receiving ■ and; transmitting licenses have at last arrived in Christchureh, and experiment-' ers may Receive them by applying to the Radio Inspector, G.P.0., Christehurth. All provisional permits are now cancelled and holders of'these permits are advised to apply for their licenses at j once. Copies of the Government Radio Regulations can bo obtained from the Government Printer, Wellington, at 6d per copy, plus Ud postage. Every amateur should procure a copy and make himself conversant with the regu- . lations. £ 6. d. Receiving License only ■•• 0 8 0 Receiving and Transmitting License, Grule 11. •■• 13 0 Receiving and Transmitting License, Grade I. ... 2 3 0 Private Broadcasting Station 2 3 0 The fee to be paid in respect of ox- ; arri' t : nns for an amateur o'erator's . certificate is for each examination or - re-examination for both Grade I. and '. Grade 11. amateurs, ss. American Amateur Reception. There are still some who do not believe this possible, and there are some with just a doubt. It appears that

New Zealand is not the only place * the- South Pacifio in which the An***' can amateurs are being heard in. iue Amalgamated Wireless. Ltd.. M*** has been receiving 6 x A.D. Major Lawrence Mott, Ayolon, Catalena Calif., very consistently. CxA.y.» using 2-50 watt tubw Weo-V-ic) and the wave-length is metres Thedistance between the two Sllot i. approximately miles. During the coming w^ r .VI will be holding testa with A-W.-b. Vi.W. Wellington Radio »*}™ \g& ae<rii.| ot the .umbrella. 'ttfpe, *«*• hißht'n Place of the present loOft 1 aerial. Radio Society ot Ohristchurch. The half-yearly general °* the Radio Souoiy of held at the club room, lla Arma*a 6t Tht election of o»c«s wmlt-d M follows:—President, Air h~ »• *-=•* laud: vice-presidents, Mr il. x. • Brown and Mr L. R. Steel; secretary, Mr V. Larsen; assistant secretary, iir E Shipiy; organiser, Mr L. Slado. The new rules and regulations were discussed, but as it was impossible to thoroughly go through tnem m °"« meeting it was decided to adjourn W the following Thursday. Tho secretary's address is 4o» Tuam street, Christchurch. Items of Interest. Experiments are being made in th« Island of luchkcith vntix what u* described as a wireless lighthouse. By means ot reue-Jtiun, wireless waves ar«. concentrated into a beam with a radiation of about 100 miles, winch revolves, and, in pasisng each point oi the compass assumes a distinctive signal. Loud speakers arc to be installed m those New York parks which at present do not possess bandstands. Motor cars and motor boats &™*™ l » osciUatious, which vary irom I to* metres to 40 metres in wave-length, be heard by experimenter, listening-in on short-wave lengths. Is the doym of the gramophone in sight? An kiglish firm is now adverrising: "Why not have your gramophone converged into a high-grade wireless receiving set?" , , I A new apparatus employing the thermonic tube for purposes of:minute measurements has been devised, bo » nsi tive is this instrument that the ben - ing of a *in steel bar caused by w«« imoact of a smoke vortex ring is demonstrable. Tho instrument has been termed the ultra-micrometer. It is rumoured that some enterprising firm has brought out a clotnea- ?„ g e which has a stranded copper centre for use in cases where the landlord objects to aenais. Ship's Call Letters. VGBC-Canadian Traveler. VOMJ —C\tv of Vancouver. VGB*— Canai£ ty Mariner. VOBJ-PsAP"*!*. vuW-Canadian Sapper. VGBL— A&e Racine VtißM-Canadian Fisher. VGBP-Canadian> VGBS—Julius Kessler. VGB iian Hunter. ion VGCK —Kiora. eacsaSn. dian Winner. Questions. Questions will be answered in this colt U mn on matters pertaining to Radio. ;Iu letters must be addressed t» !-Eleotra." care the Ixlitor. ™ ; Press" and must reach thu «jffi«» »«» iEff'fluui 12.30 P.m on Mondays Write on one. side of the paper omj. ! All drawings, etc., to be on a eep-raU. ! sheet of paper. . . y i uys"—The maximum oi yow co" 'i« 1340 'metres. The fundamental wave Inffth of your aerial is approximately , Tmet/J 0 The coil W *%*£* | sent will be suitable tor »*?*****' but I would advise you to make one to tune up to 600 metres oniy.