XI. APPLICATIONS. 3 5 1 



151O. Alarum with Centrifugal Hammer. Used in con- 

 nexion with Cooke and Wheatstone's first needle instruments. 



Moved by wheelwork and mainspring; released by an electro-magnet. 

 Used in connexion with Cooke and Wheatstone's first needle instruments. 



1513. Thunder Pump." 



Henley's Magneto-Electric Machine, used for ringing alarums, etc., com- 

 monly known as the " Thunder Pump." Used by the Electric Telegraph 

 Company. 



1554. Early form of Wheatstone's Resistance Coils. 



1552. Bain's Chemical Telegraph. (Incomplete.) First 

 form of recording Instrument used in England, 1846. 



The chemically -prepared paper is wrapped round the cylinder. An iron 

 style presses on the paper and writes dots and dashes in a spiral line as the 

 cylinder moves endwise while revolving. 



The signals are formed manually by pressing a key, or automatically by a 

 spring, making contact through perforations previously punched in a paper 

 ribbon. 



1551. Bain's Perforator for double dot or Steinheil 

 Alphabet, 1846. 



The perforations are made by circular punches on a baud of paper. The 

 third key on the right is for advancing the paper without punching, for 

 spacing between letters and words. 



1532. Bain's Chemical Telegraph as used by the Electric 

 Telegraph Company in 1850 in place of the double needle. 



The paper ribbon was prepared with yellow prussiate of potash and nitrate 

 of ammonia ; the style is of iron. The Steinheil code, dots in two parallel 

 lines, was occasionally used, but was entirely superseded by the Morse code of 

 dots and dashes. 



1531. Morse Embosser., about 1853. Used by the Electric 

 Telegraph Company. 



This superseded the Bain instrument and was in its turn superseded by the 

 inkwriter. 



The dots and dashes of the Morse alphabet are made by a rounded steel 

 point fixed at one end of a lever, the other end being furnished with an 

 armature and attracted by an electro-magnet worked by a relay and loca 

 battery. 



1533. Various forms of Ink-writers. (Old.) 

 a. Breguet's ink-writers. 



6. Ink -writer with inking pad and reservoir. 

 c. Do. do. ink bottle. 



1529. Keys used with the Bain and Morse Telegraphs, by the 

 Electric Telegraph Company. 



a. Simple spring key. 



6. Key for sending a short reversal after each signal, two sets of batteries 

 being required. When the key is up, the line wire is connected to the 

 receiving apparatus. .''"*{* 



