302 SEC. 10. ELECTRICITY. 



1521. Highton's Needle Telegraph, 1848. Used by the 

 British and Irish Magnetic Telegraph Company 



A horseshoe or circular magnet within a circular coil, arid -worked by a 

 reversing key, is used. 



The signals are similar to those of Cooke and Wkeatstone's single needle, 

 but a different alphabet is adopted. 



Needle and coil used with this instrument 



1522. Highton's Needle Telegraph, smaller form. Used 

 by the British and Irish Magnetic Telegraph Company. 



Identical in construction with the original form, which it superseded. 



1523. Highton's Needle Telegraph, last form. Used by 

 the British and Irish Magnetic Telegraph Company. 



With key detached. Identical in construction with the two former instru- 

 ments, but the signalling key is detached from the indicating portion, and 

 placed near the edge of the desk before the operator for greater convenience 

 of working. 



1524. Reversing Signalling Key, for Highton's simple 

 Needle Telegraph. Also used with Bright's Bell Instrument. 



This is a substitute for the drop handle Commutator of Cooke and Wheat- 

 stone's needle instrument. When the right-hand key is depressed a current in 

 one direction is sent out to the line, and the pointer of the indicating instru- 

 ment moves to the right. When the left-hand key is depressed a current in 

 the opposite direction is sent, and the pointer moves to the left. 



1525. Bright's Bell Instrument, 1855, with Relay. 

 Used by the British and Irish Magnetic Telegraph Company. 



The simple needle alphabet is produced by striking two bells of different 

 tones, the hammers being actuated by electro-magnets worked by a relay and 

 local battery. The relay is double-acting, and consists of two electro-mag- 

 netic bobbins placed side by side, their ends being furnished with pole pieces 

 turning inwards. Between these pole pieces at each end of the bobbins the 

 ends of permanently magnetised needles pivoted on vertical axes play ; these 

 needles are so placed as regards their polarity, that a current in one direction 

 moves the needle which closes the local circuit of the right-hand bell, and a 

 current in the opposite direction moves the other needle which closes the 

 local circuit of the left-hand bell. The signalling key used with this instru- 

 ment is similar to that used with Highton's single needle. This instrument 

 superseded Henley's magneto-electric system. 



1526. Bright's Direct Bell Instrument, 1870. (Model.) 



Model of a Bright's bell instrument, in which the bells are struck by 

 hammers attached to the magnetic needles of the relay. 



1527. Highton's Gold Leaf Telegraph, 1846. 



. A movable conductor formed by a strip of gold leaf is placed in 

 proximity to one pole of a permanent bar magnet, and moves to the right 

 or left of its normal position according to the direction of the current 

 passing through it. It was designed as a substitute for the needle and coil 

 of Cooke and Wheatstone's instrument, but was never brought into practical 



