XI. APPLICATIONS. 315 



1576s. Wheatstone's Portable ABC Telegraph, 

 specially arranged for Military Purposes. 



The British Telegraph Manufactory, Limited. 



1576t. Wheatstone's Alphabetical Magneto-Electric 

 Telegraph. The British Telegraph Manufactory, Limited. 



1576u. Polarised Morse with Wheatstone's System 

 of Adjustment and Inking. 



The British Telegraph Manufactory, Limited. 



1576v. Translating Morse with Wheatstone's System 

 of Inking. The British Telegraph Manufactory, Limited. 



1576w. Resistance Box. 



The British Telegraph Manufactory, Limited^ 



1576x. Resistance Box. 



The British Telegraph Manufactory, Limited. 



1576y. Large Standard Resistance Box. 



The British Telegraph Manufactory, Limited. 



1576z. Commutator. 



The British Telegraph Manufactory, Limited. 



1582. Meidinger's Galvanic Element, 



Prof. Dr. Meidinger, Carlsruhe. 



1583. Ditto of a larger size. 



Prof. Dr. Meidinger, Carlsruhe. 



Are for working telegraphs, electric clocks, and bell apparatus, also for 

 electroplating in silver or gold. 



1584. Box, containing a battery of 21 elements for pro- 

 ducing constant currents for medical use. Entirely new con- 

 struction of the exhibitors. Prof. Dr. Meidinger, Carlsruhe. 



The glasses are filled with a solution of bichromate of potash and 

 sulphuric acid in water. The gutta-percha covered rods are introduced into 

 the wide glass, the wires into the mercury tube, with which is connected a 

 platinum wire, leading to the platina sheets, After operation the metal con- 

 nexions are taken out of the glasses. The liquid is let remain in the glass till 

 it is used out ; it may serve for 50 one hour operations. In transport, the 

 liquid does not escape, even in violent shaking. The stoppers with inserted 

 glasses are never taken out. rilling is done by pouring the liquid through 

 the wide tube ; emptying by inverting the glass, when the liquid flows out 

 through the fine air passages. The gutta-percha under the zinc is gradually 

 worn away in proportion as the (amalgamated) zinc is dissolved ; only about 

 a millimetre of free surface of zinc is necessary. The narrow trough is filled 

 with very dilute zinc vitriol, and serves, through displacement of the zinc pole, 

 in regulation of the strength of current. On drawing out a peg, the liquid 

 escapes below into a central vessel. 



