SKPTEMllF.n 1. 1000 1 



KNOWLEDGE 



193 



Founded by RICHARD A. PROCTOR. 



LONDON: SEPTEMBti: I. I'.'nn. 



E. Gore, i'.h.a.s. 

 Alex. B. MaoDouall. 



(Illustrated) 



Note liv K. Walter 



CONTENTS. 



High-speed Telegraphy. Bv Cuas. U. Gakiand. {lllus- 



trattii) " 



The Pygmies of Asia. B\ R. Ltdkkkei!. {Illustrated) .. 

 Astronomy without a Telescope. — VIII. Four Variable 



Stars. By K. Walter MArsDBE. f.r.a.s. 

 Jupiter and his Markings. By W. F. Dknnino. f.k.a.s. 

 * Jupiter and liis Marl<ings. {Plate) 

 The Hundred Brightest Stars. By J. 

 Letters : 



Hot avd Dry summers. Bv 



{Illiislrated) 

 Cbescentshaped Images of the SrN during the 



EctirsE. By E. Pierce. 

 ASTEOIOQY. By B. Chati-ev. 



Macndbr 



MiBA Ceti. By 0AVID Flanebt 



TuE HrroTHETirAL PLA^•BT. By G. McKenzib Knigiit 

 British Ornithological Notes. Conducted by Habby F. 



WlIHBBBT, P.Z.S., M.B O.tr. ... 



Production of Colour Effects (Illustrated) 



Eros and the Astrographic Conference 



Notices of Books 



Books Hbceited 



The Karkinokosm, or World of Crustacea,— 



The Many-Twinkling Feet. By the Rev. Thomas 



R. R. Stbbbino, M..V., F.B.S., F.L.S., T.Z.8. (Illustrated) 



Sir John Murray and the Black Sea 



Microscopy. By John H. Cooke, f.l.s., p.g.s. 



Notes on Comets and Meteors. By W. F. Denning, f.b.a.8. 



The Face of the Sky for September. By A. Fowleb, 



P.B.A.8 



Chess Column. By C. B. Locock, b.a. 



1 '.).■? 

 lil!) 



JIKI 



2Ht 

 204 



206 

 206 



20C 

 207 

 207 

 208 

 211 



211 

 21 :) 

 211 

 2U 



215 

 215 



HIGH-SPEED TELEGRAPHY. 



By Chas. H. Garland. 



Last year the lovely little town of Como held a great 

 fete to celebrate the Volta centenary. Truly it has cause 

 for pride. The town made famous by the two Plinys 

 was the birthplace of the man who discovered a force 

 which bids fair to revolutionise the industry of the 

 world. In discovering the pile, the forerunner of all 

 the electrical batteries we know to-day, Volta made 

 possible the production of the first constant current of 

 electricity, and thus laid the foundation of all later 

 developments. 



A part of the celebrations consisted in a Congress of 

 telegraph experts from all comers of the civilized globe. 

 The world was ringing with the name and fame of 

 Marconi, a native of Bologna, and the attention given 

 to his wireless telegraphy absorbed the public interest, 

 so it escaped notice that at one of the sittings of the 

 Congress, Hofrath Josef Kareis, of Vienna, gave a brief 

 description of one of the most striking inventions of 

 modern times — the work of Anton Pollak, a Hungarian 

 electrician, and Josef Virag, a Hungarian mechanician. 

 It was claimed for this marvel that it could transmit 

 telegraphic messages over long distances at the astound- 

 ing rate of sixteen hundred words per minute. 



In order to understand the full significance of these 

 llgurcs, we must take a brief glance at modern telc- 

 ijraphy and the speeds hitherto attained. Nearly the 

 whole of the English telegraph work is carried out by 

 some adaptation of the Morse system, involving the use 

 of certain signals produced either by some printing 

 api)ar:itus for sight reading, by some sounding apparatus 

 for reading by the car, or by any other method which 

 will appeal to the senses. It is employed in flag signal- 

 ling, lamp and heliograph signalling, and in some half- 

 dozen systems of telegraphy. The short and long 

 signals, however produced, are known as " dots ' and 

 " dashes." Thus, a dob followed by a dash is A. A 

 dash followed by three dots is B. Dash, dot, dash, dot, 

 is C. and so on. 



The fastest method of telegraphy, unassisted by auto- 

 matic appliances, is known as the " sounder." This i,s 

 essentially a small hammer which, in response to 

 currents sent from the sending oflico, strikes upon a 

 brass upright and produces a short or longer tajj, which 

 the listening telegraphist translates into writing. By 

 this system a good telegraphist can send and receive, 

 for a short period, as many as 45 words per minute. 

 The speed at which a clerk can receive is limited, for all 

 practical pui-jooscs, by the speed at which he can write. 

 So for an apparatus which is read by sound, and leaves 

 no printed record of the signals which can be afterwards 

 transcribed, a higher speed is useless. 



There are on the average three signals to each letter 

 of the Morse alphabet, and the length of the telegraphic 

 word is, as a rule, five and a half letters. In order, then, 

 to receive 45 words in a minute, a telegraphist must 

 discriminate the various characters of 720 signals or taps. 

 As the space between the taps is of almost equal im- 

 portance with the taps themselves, he has to measure 

 the length of an equally large number of silent intervals. 

 A clearer idea of what this sjJeed means can be obtained 

 if we remember that a watch ticks about 160 times per 

 minute. 



In the Wheatstone system the sending is done by means 

 of an automatic transmitter. The perforating of the 

 ribbons is performed very rapidly, and I have seen tele- 

 graphists work at the rate of over 50 words per minute. 

 A large number of telegraphists can be employed in 

 preparing ribbons which may be continually passed 

 through the transmitter at the rate of 400 words per 

 minute. This means that 6,600 signals are sent over 

 the wire in one minute, a speed seldom exceeded in 

 actual working. 



At the receiving ofiice the signals are printed on a 

 narrow green ribbon, and consist of shorter or longer 

 black lines, which represent the conventional dots and 

 dashes. When the green ribbon has been received it is 

 cut up into sections and distributed among a number 

 of writing clerks, who transcribe it. In this manner 

 it is possible to keep a large number of clerks fully 

 employed at either end of the wire, and so avoid what 

 is the chief expense in telegraphy — the building of new 

 trunk lines and maintaining them in repair. 



Up to the time of the invention of the Pollak-Virag 

 system, the Wheatstone automatic telegraph was the 

 most rapid of the high-speed telegraph systems. It is 

 true that an American system, invented by Crehore 

 and Squire, attained a tremendous speed in the experi- 

 menting room, but the details were so complex, and the 

 electrical difficulties so great, that it was never put 

 to practical use. 



The Pollak-Virag telegraph will send 100,000 words 



