MISCELLANEOUS PRACTICAL APPLICATIONS. 



331 



syphon to move sidewise with the utmost freedom, and therefore 

 the tip of the syphon cannot be allowed to rest against the mov- 

 ing paper. This difficulty was overcome in the early form of the 

 syphon recorder * by keeping the ink reservoir and syphon highly 

 charged with electricity by means of an influence machine, thus 

 causing the ink to issue from the tip of the syphon in the form of 

 a fine jet. In the present form of the recorder the syphon is 



Fig. 34. 



kept vibrating rapidly against the paper so as to trace a finely 

 dotted line as the paper moves while at the same time the side- 

 wise motion of the syphon is not hindered by friction. The essen- 

 tial features of the syphon recorder are shown in Fig. 34. 



* The syphon recorder was devised by Lord Kelvin, who contributed more, perhaps, 

 to the development of transatlantic telegraphy than any other man. In an article by 

 Professor W. E. Ayrton, which appeared in the London Times shortly after Lord Kel- 

 vin's death (reprinted in Popular Science Monthly for March, 1908), much interesting 

 information is given concerning what Kelvin did for submarine telegraphy. " When 

 signals through the 1858 Atlantic cable became weak, and a message from the Presi- 

 dent to our Queen took thirty hours in transmission although containing only 150 

 words, and which would need only three or four minutes to transmit through any one 

 of our good Atlantic cables of to-day, the only remedy of those who looked down 

 upon the theories of the young Glasgow professor was to use Whitehouse's "thunder 

 pump," a magneto-electric machine which produced a sudden large electromotive 

 force when the armature of the permanent magnet was jerked off the poles of the 



