XI. APPLICATIONS. 361 



Brown earthenware insulator, with zinc cap (1850V 



Do., with groove for wire. 



Do., glass instead of earthenware. 



(1851) brown earthenware. 



glass. 



Clark's invert insulator, corrugated. 

 Varley's double-cup insulator, fitted. 

 Ditto, in separate parts, 1862. 

 Varley's No. 1 1 wire double-cup insulator. 

 Brown earthenware insulator called (Z). 

 Double shed invert compressed ware. 

 Single _ 



South Devon invert insulator (brown). 



(white). 



Andrews' invert with ebonite inner shed. 

 bolt tube 



bolt tube and shed. 



Ebonite insulator, single shed. 

 Old form of shackle. 

 Bright's shackle. 

 Modern terminal insulator. 



TELEGRAPHIC APPARATUS CONTRIBUTED BY THE IMPERIAL 

 GERMAN TELEGRAPH DEPARTMENT. 



1608. Copy of the Electro-chemical Telegraphic Appa- 

 ratus of S. T. Sommering, the first German telegraphic appa- 

 ratus, constructed in 1809. 



1609. Drawings of the Russian Councillor Schilling's 



(of Kannstadt) Apparatus, being the first needle telegraph (two 

 sheets). 



1610. Copy of the Electro-magnetic Telegraphic Appa- 

 ratus of Gauss and Weber, of Gottingen, made and used from 1833 

 to 1838. It consists of 



(a.) The signal sender (by means of induced current). 



(b.) The signal receiver (a magnetic rod with multiplying coil 

 and mirror). 



(c.) Telescope for reading off the deflexions of the magnet ; with 

 stand. 



1611. Copy of the Electro-magnetic Telegraphic Appa- 

 ratus of Steinheil, in Miinchen, 1837. 



1612. Electro-Magnetic Indicator, combined with type- 

 printing apparatus of Siemens, of Berlin, constructed in 1846. 

 Patented in Prussia. 



1613. Bell Machinery for Railways (Siemens), 1847. 



1614. First Gutta-percha Press for covering conductors 

 with insulating material without a seam. After Siemens' model, 



