XI. APPLICATIONS. 347 



IGSOa. First Electro-magnetic Needle Telegraph, in- 

 vented in the year 1830 by Baron P. L. Schilling (born in 1786 

 at Reval), consisting of : 



Two electro- magnetic alarum apparatus ; two ditto, and gyro- 

 tropes (key-board, indicator) ; one current indicator ; one multipli- 

 cator for the signs (sign receiver) of the magnetic needle to the 

 right or to the left respectively, turning of the white or black 

 side of a paper disc towards the spectator. 



Physical Science Cabinet of the Imperial Academy of 

 Sciences, St. Petersburg. 



1508b. Portion of the first line of Telegraph, laid by 

 Cooke and Wheatstone in 1837 between Euston and Camden 

 stations. It consists of five wires and was worked with their 

 earliest or " hatchment " dial instrument. Latimer Clark. 



1419. Fart of Cooke and Wheatstone's First Working 

 Telegraph. Edinburgh Museum of Science and Art. 



1680. Specimen of the First Telegraph Line, 1837. 



R. S. Culley. 



This specimen of the first Telegraph line was dug up on the railway incline 

 between Euston and Camden. It was laid down in connexion with the first 

 experiments made with Cooke and Wheatstone's earliest instrument in 1837. 



1689. Cooke and Wheatstone's ABC Instrument, 



1840. Reid Brothers, London. 



The escapement wheel on the axle of which the pointer is fixed is con- 

 trolled by electro-magnets. 



The communicator is outside, and concentric with the indicator dial, and 

 consists of a cog-wheel working into two smaller wheels. The cog-wheel is 

 turned by a handle, and the battery contacts are made by small wooden 

 cylinders inlaid with metal fixed on the smaller wheels. 



The wheelwork is driven by a mainspring. 



1690. Nott and Gamble's Step by Step Fointer Tele- 

 graph, 1846. Reid Brothers, London. 



Electro-magnets act on a ratchet-wheel by means of clicks attached to their 

 armatures. On the axle of the ratchet-wheel the pointer is fixed ; the latter is 

 moved forward through a space equal to the distance between two letters for 

 each making and breaking of the battery contact. A simple tapper or pedal 

 key is used for sending the currents, and the pointer is allowed to rest for a 

 short interval when it is opposite to the letter desired to be indicated. The 

 instrument is furnished with an alarum, the bell being struck by a hammer 

 attached to the armature of an electro-magnet provided for the purpose. 



1681. Cooke and Wheatstone's Double-Needle Tele- 

 graph, with Alarum. Earliest form, with 6-inch coils and 

 astatic needles. Reid Brothers, London. 



These instruments were used on the line erected between Paddington and 

 Slough for the purpose of exhibiting the invention in 1844, and were the 

 identical instruments by the aid of which Tawell was caught. 



