jVA rURE 



[May 2, 1 90 1 



having been introduced by means of which the recorded 

 message is written in ordinary Latin characters and can 

 consequently be read by any one. In order to do this it 

 is necessary to give the mirror on the receiving instru- 

 ment a horizontal as well as a vertical motion, and for 

 this purpose two circuits are needed and two telephone 

 diaphragms, one giving the mirror vertical movements 

 and the other horizontal. A single metallic loop is em- 

 ployed, one telephone beiny put in the loop and the 

 other between the loop and earth. Horizontal move- 

 ments of the mirror, to right and to left, are produced by 

 currents passing round the loop in one direction or the 

 other respectively, and vertical movements by currents 

 passing from the loop to earth ; in this second case an 

 upward movement is produced by a current in one 

 direction and a downward movement by a current in the 

 opposite direction, and also a downward movement of 

 double the distance by a current at double the normal 

 voltage. 



PERFORATIONS. 



»OTIC»L. 



r\l\p^ifnA- 



Fig. 4. 



HORIZOKTiiL. 



RESULTANT 



The line currents are sent by means of perforated strips 

 of paper much in the same way as in the Wheatstone 

 transmitter, but five strips are used, three to give the 

 vertical components and two for the horizontal. These 

 strips are shown in Fig. 3 ; the rows marked i, ii and iii 

 give the vertical components, the first row giving the tall 

 letters and the third the deflections of double amplitude 

 for the letters with tails ; rows iv and v give the horizontal 

 components. Deflections of a fraction of the normal 

 amplitude are given by contacts lasting a sliorter time by 

 means of the small perforations as seen in rows ii, iv and 

 v. The perforations are so arranged tliat the combina- 

 tion of the vertical and horizontal movements of the 

 mirror (as seen in Figs. 4 and 5 respectively) gives the 

 Latin characters (Fig. 6), and all the perforations for one 

 letter are punched at the same time by means of a special 

 machine of the typewriting kind. To obviate the diffi- 

 culty of having to use a rapidly moving narrow strip of 

 sensitised paper to receive the photographic record, as m 

 a tape machine, a very neat deviceis employed. The 

 source of light is the filament of an incandescent lamp, 

 KO. 1644, VOL. 64J 



which is surrounded by an opaque cylinder in which a 

 helical slit is cut. This cylinder is revolved, and as it 

 turns the part of the filament acting as a source of light 

 moves from left to right as the slit uncovers in succession 

 the various portions of the filament ; at the same time, the 

 spot of light reflected on to the recording paper, which is 

 a broad band of sensitised paper, will also move from left 

 to right, thus writing a complete line on the paper ; at 

 the end of a complete revolution the spot will return 

 again to the left-hand side of the paper band and will 

 proceed to write a new line, this new line being brought 

 under the other by a movement imparted to the band of 

 paper. The message is thus directly obtained as an 

 ordinary written message in lines one below the other, 

 and the system has thus the great advantage over all 

 Morse methods that the message has not got to be de- 

 ciphered and transcribed by the receiving telegraphist. 

 With this apparatus it is said that a speed of 1000 words 

 a minute can be obtained. 



The Pollak-Virag system, although in its most recent 

 form it gives a record in ordinary handwriting characters, 

 must not be confused with those systems designed to trans- 

 mit the actual handwriting or drawing of the signaller. 

 Several instruments, under the name telautographs, 

 have from time to time been devised for this purpose, 

 and the late Prof Elisha Gray was, we believe, engaged 

 on the perfecting of an invention of a telautograph at the 

 time of his death. The attempts at solving the problem, 

 which is, it must be confessed, a very fascinating one even 

 though the very extensive utility of such an instrument 

 may be questioned, have not, so far, proved very success- 

 ful. Last year, however, there appeared in the technical 

 Press descriptions of a telautograph which is the invention 

 of Mr. Foster Ritchie, and which seems to have got over 

 the difficulties in a very practical manner. In the 

 Ritchie telautograph the message is written with an 

 ordinary pencil ; by means of levers attached to this 

 pencil its movements are made to regulate the currents 

 sent through the transmitting lines, and these currents in 

 their turn regulate the motion of a pen at the receiving 

 end. By an ingenious arrangement the receiving pen 

 only makes marks on the paper when the transmitting 

 pencil is pressed down on the writing table. The 

 receiving pen exactly reproduces the characters written 

 at the transmitting end, which can be written at the 

 ordinary speed of handwriting. We hope on a later 

 occasion to give a more detailed description of the 

 apparatus. 



We may finally describe an invention which has aroused 

 considerable interest amongst our American cousins, 

 namely, Dr. Pupin's system of long distance and oceanic 

 telephony. Dr. Pupin has, we understand, disposed ol 

 his American patent rights to the American Telephone 

 and Telegraph Company for a very large sum of money, 

 which shows that this company have great confidence in 

 the invention. The difficulty of carrying out successful 

 telephony over a great length of line arises out of the 

 fact that the line possesses both resistance and capacity ; 

 this is especially the case with submarine cables in 

 which the capacity is large. These properties produce 

 both attenuation and distortion of the transmitted signals, 

 the arrival current being both very much weaker and 

 different in character to the current sent into the cable at 

 the transmitting end. The alteration in character is due 

 to the fact that the more rapidly varying currents are 

 more easily attenuated ; if a varying current be sent into 

 the cable by speaking into a telephone at the transmitting 

 end this may be analysed, just as the sound to which it 

 corresponds may be analysed, into a fundamental vibra- 

 tion and a number of higher harmonics ; the higher har- 

 monics will, after travelling along the cable to a certain 

 distance, become so attenuated that they will be incap- 

 able of producing any effect on a receiving telephone, so 

 that such an instrument, if placed at this point, will only 



