XI. APPLICATIONS. 321 



instruments would be acted upon, and consequently advance in the direction 

 of the wire communicating with the battery, and so automatically close the 

 electric circuit by making contact with such wire. 



Whether such contact be made with the thermometer and aneroid barometer 

 together, or by one singly, the current or circuit is closed and makes instant 

 and simultaneous contact with the indicating and alarm apparatus ; thus giving 

 instant and positive indication of where danger is developing or assistance 

 required. 



1673. Electric Domestic Bells (three). J. Round. 



1674. Electric Detective Bells (three). J. Round 



1675. Apparatus for sending simultaneously in opposite 

 directions Telegraphic Despatches, between two stations with 

 one single wire in the line. 



Elie Wartmann, Professor of Natural Philosophy in the 

 University of Geneva. 



A full description is to be found in the number for March 1856 of the 

 " Bibliotheque universelle de Geneve." The keys, when worked, close two 

 different circuits, which are to be of such' directions and intensities that they 

 neutralise each other in the two sets of coils of the branches of the electro- 

 magnets. 



1678. Apparatus for transmission of two simultaneous 

 Telegrams in the same Telegraphic Wire, from one station to 

 another. 



Elie Wartmann, Professor of Natural Philosophy in Ike 

 University of Geneva. 



A description of the method and apparatus is printed in the No. for 

 November 1860 of the "Archives des Sciences physiques et naturelles" of 

 Geneva. 



1679. Apparatus for permitting any two Stations on the 

 same Telegraphic Wire to communicate immediately without the 

 aid of the intermediate ones, so that the despatch remains secret 

 between both. 



Elie Wartmann, Professor of Natural Philosophy in the 

 University of Geneva. 



For complete description see the No. for May 1853 of the "Bibliotheque 

 universelle de Geneve." It consists of the following parts : 



a. The Sender ; b. the Regulator ; c. the Indicator ; d. the Inter- 

 rupter. The principles of the instrument are: 1. To break the communi- 

 cation of every intermediate station with the earth; 2. To maintain the 

 contact of their electro-magnets with the poles in order to facilitate the trans- 

 mission of direct currents between the two stations to be united ; 3. To let 

 the officer in the station from which the despatch originates know that it is 

 really received in the proper one ; 4. To cut off immediately the communica- 

 tion after the receipt of an answer ; 5. To reinforce the current of the battery 

 in the first station by means of the batteries in all intermediate stations. 



1676. Electrical Alarum, with Leclanche's battery. 



Mariais, 

 89508. X 



