XI. APPLICATIONS. 323 



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's Step by Step Pointer Telegraph, 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. 



169Oa. Double Indexed Telegraphic Post, with alphabe- 

 tical receptor, indicator, and printer at will ; manipulator (Cham- 

 brier's system) in every direction. M. Deschiens, Paris. 



The whole of this apparatus is enclosed in a case for protection. 



1691. Pocket Telegraph Instrument and Writing 

 Apparatus, arranged for reversing. 



Siemens and Halske, Berlin. 



1692. Magnetic Telegraphic Apparatus, with printer. 



Siemens and Halske, Berlin. 



1693. Pocket Printing Apparatus, with feeder. 



Siemens and Halske, Berlin. 



1694. Quick Composer, with printer. 



Siemens and Halske, Berlin. 



1694a, Printing Telegraph, invented by M. H. Jacobi, 

 academician, in the year 1850. Two uniform apparatus for two 

 stations. 



Physical Science Cabinet of the Imperial Academy of 

 Sciences at St. Petersburg. 



1695. Apparatus for making contact to show the height of 

 water with float, rod-chain, counterpoise, and water tube. 



C. $ E. Fein, Stuttgart. 



This is self-acting, and registers at any distance off the water-level in a 

 reservoir, &c. 



X 2 



