310 SEC. 10 ELECTRICITY. 



same direction. Two adjustments are provided, one the ordinary spring 

 adjustment, the other for moving the needles nearer to or further from the 

 poles. 



This arrangement is much more sensitive than the old form of nou-polarised 

 relay with horseshoe electro-magnet and armature. 



1564a. Double-current Key, with levers instead of the 

 ordinary springs. 



Series of Apparatus far Recording the Steinheil or Single 

 Needle Code. 



The first recording telegraph Avas SteinheiPs, completed in 1837. The 

 code was formed of dots recorded in two lines, those in one of the lines being 

 formed by the + , those in the other line by the current. The code resem- 

 bles that of Cooke and Wheatstone's single needle. 



The system, if ever brought into practical use, was superseded by that of 

 Morse, in which the code is comprised of marks of varying lengths. 



But, as the dash occupies thrice the space and thrice the time of a dot, 

 attempts have been made from time to time to introduce apparatus regis- 

 tering the Steinheil or single needle alphabet. 



1564b. Unpolarised Recorder, for registering the single 

 needle code. 



1564c. Unpolarised Recorder, for registering the single 

 needle code. 



1564d. Polarised Recorder, for registering the single 

 needle code. 



1564e. Polarised Recorder, for registering the single 

 needle code. 



The negative current prints a dot (), the positive current two dots I ) 



transversely. The first represents the dot, the second the dash of the Morse 

 alphabet. The letter A is written thus . . . . J . 



1564f. Non-polarised Recorder, for registering the single 

 needle code. Richard Herring's system. 



The negative current prints a dot ( ), the positive current a transverse 

 dash( J ), so that the printing resembles the Morse alphabet. The letter A 



is written thus I 



1564g. Modification of Wheatstone's Automatic 



Transmitter, used in connexion with Richard Herring's 

 system. 



1564h. Modification of Wheatstone's Perforator, for 



his automatic system, arranged to punch the single needle code, 

 used in connexion with Richard Herring's system. 



15641. Specification of John Imray, No. 2,574-1862. 

 1565. Pony Sounder. 



This instrument is of American origin ; it is used instead of the ink -writer on 

 some of the lines of the Postal Telegraph Department, the dots and dashes of 



