512 



NATURE 



[April 29, 1875 



tance to receive the next hole ; and thus, by successive 

 depression of the respective punches, the holes are cut in 

 the paper ribbon in the necessary sequences to represent 

 letters and groups of letters to form words. The centre 

 punch, besides mechanically spacing the perforations to 

 ensure their proper passing through the " transmitter," also 

 by individual pressure spaces the distance between the 

 letters and words of the message. The appearance of the 

 paper ribbon thus prepared is shown full size at Fig. 20. 

 Thus the message is written away from the wire, and the 

 time taken up in its preparation is independent of loss of 

 revenue on capital incident to the unnecessary occupation 

 of the circuit by the slow and protracted results of manual 

 labour. 



The second part, or "transmitter" of the automatic 

 system, is the apparatus which automatically sends into 

 the wire the sequence of currents, as prepared by the 

 "perforator." In this process, performed much in the 

 same manner as the perforated Jacquard card regulates 

 the successive elevation or derrcssion of the warp-threads 

 in the loom, the perforated ribbon-paper strip is caused 

 to advance step by step through the machine by the suc- 

 cessive gr'p of an oscillating cradle, regulated to advance 

 the paper a distance exactly corresponding to the spacing 

 of the holes by the " perforator," so that by the action of 



a rising pin, elevated and depressed alternately at each 

 toand-fro motion of the rocking frame, the message 

 ribbon is automatically and mechanically impelled for- 

 ward. Two other spring contact pins, representing 

 respectively the contact with the positive (copper) or 

 negative (zinc) currents of the battery (which may be 

 either magneto- or voltaic- currents of electricity), are 

 actuated by the same mechanical movement, by means of 

 eccentric cam arrangements. Thus, when the perforated 

 paper ribbon is carried automatically forward step by 

 step in rapid succession by the action of the central pin, 

 if a " current-passing" perforation is in position at the 

 moment of passing the paper ribbon with either pin, the 

 respective pin will rise through the hole and make a 

 metallic contact with the battery through the instrument, 

 sending a current into the line in the one or other direc- 

 tion, according to the position of the perforation and the 

 rising of the respective pin. If no perforation in the 

 paper ribbon is in position at the time of the automatic 

 elevation of the respective pins, they fall back by the 

 compensating influence of adjusting springs, and a mute 

 movement is made by which no current from the battery 

 is passed into the circuit. It will thus be understood that 

 the action of the transmitter is also threefold as regards 

 the passing of the current and the motion of the paper. 



\^c-- 



First, each rocking of the cradle carries the paper ribbon 

 for\vard the exact distance that the depression of the key 

 in the " perforating " machine advanced the message slip. 

 Secondly, when the paper ribbon has been thus advanced, 

 it is momentarily held in suspense to admit of the entrance 

 of the respective pin, completing battery contact according 

 to the position of the hole ; and thirdly, if no perforation 

 representative of the passing of a current into the line is 

 in position, a mute movement of the pin is made, and the 

 paper is simply automatically advanced forward by a 

 regular step by step movement. In addition to these 

 three mechanical cam and eccentric movements in con- 

 nection with the advancement of the ribbon, the elevation 

 of the pins, and the passing of a current into the circuit 

 from the concurrence of a perforation in the paper ribbon 

 and the rising of a pin, a fourth important electrical con- 

 tact movement takes place at each successive motion of 

 the rocking cradle, independent of the rising of the pins, 

 namely, that of momentarily making contact between the 

 line wire and the earth after each successive elevation of 

 either current-passing pin. The importance of this dis- 

 charge to earth to clear the line has previously been 

 pointed out as arising from the sensible retention in the 

 insulated wire of a portion of the transmitted current, 

 which, unless drawn i ut, would interfere with the integrity 

 of the succeeding current, reducing the transmitting speed 

 of the wire. 



By a very beautiful arrangement of electrical contacts 

 (perfected by Mr. A. Stroh, to whose great skill as 

 applied to electrical problems of a mechanical nature 

 Wheatstone is indebted for the absolute perfection of the 

 mechanism in his automatic telegraph — the ABC tele- 

 graph — and the sympathetic electric clock movements), 

 after each successive elevation of the pins, the circuit wire 

 is connected momentarily to earth ; this takes place at 

 each motion of the rocking cradle, whether a pin enters a 

 p:rforation in the paper ribbon or not. Thus the line is 

 connected for discharge at regular intervals, irrespective 

 of its charge by the elevation of a pin, a current only 

 passing into the line by the contact made with the battery 

 on the elevation of either pin. 



In this mechanical arrangement, therefore, the neces- 

 sary contacts with the battery and the regular discharge 

 of the line are produced without recourse to manual 

 labour ; mistakes are avoided, for machinery never forgets 

 its registers or makes false records, both of which errors 

 are inseparable from the employment of the human hand 

 and brain. Man, though a thinking being, is not a 

 machine, and it is not possible ever to turn the human 

 frame into an automaton ; were this so, the value of 

 invention would be at an end, and the accurate perform- 

 ance of machinery at a discount. 



{To be continued.) 



