Masterpieces of Science 



by a mischievous boy as, with a slight and al- 

 most imperceptible motion of his hand, he has 

 used a bit of looking-glass to dart a ray of re- 

 flected sunlight across a wide street or a large 

 room. On the same plan, the extremely minute 

 motion of a galvanometer, as it receives the 

 successive pulsations of a message, is magnified 

 by a weightless lever of light so that the words 

 are easily read 'by an operator (Fig. 61). This 

 beautiful invention comes from the hands of Sir 



Fig. 63. Siphon record. "Arrived yesterday " 



William Thomson [now Lord Kelvin], who, 

 more than any other electrician, has made 

 ocean telegraphy an established success. 



In another receiver, also of his design, the 

 siphon recorder, he began by taking advantage 

 of the fact, observed long before by Bose, that a 

 charge of electricity stimulates the flow of a 

 liquid. In its original form the ink-well into 

 which the siphon dipped was insulated and 

 charged to a high voltage by an influence-ma- 

 chine; the ink, powerfully repelled, was spurted 

 from the siphon point to a moving strip of paper 

 beneath (Fig. 62). It was afterward found 

 better to use a delicate mechanical shaker which 

 throws out the ink in minute drops as the cable 

 current gently sways the siphon back and forth 

 (Fig. 63). 



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