362 Locke 



' axis of rotation of the lever recording intervals of time to the 

 Jaquet Time Marker, which thus becomes an electric signal as 

 well. A description of this will be published later. 



The Polygraphic Use of a Single Simple Electromagnetic Signal. 



In order to get the most polygraphically out of an ordinary electro- 

 magnetic signal, it is essential that it be used to record time-intervals of 

 not much less than one second, by closures of the chronograph-circuit of 

 markedly unequal length to that of the openings alternating with them. 

 Absolute continuity of the time-record must also be not all important, a 

 condition very rarely unfulfilled in the present perfection of recording 

 apparatus. Given a signal writing seconds by short makes of the battery - 



Fig. 2. — Records of time in seconds (every tenth second missed) ; of makes and breaks of a constant 

 current, and of " tetanisation " by means of the interrupter of an ordinary Du Bois coil. 

 The speed of the drum was increased between each tracing from above downwards. In the 

 lowest tracing the interruptor was continuously in action, and two clock-contacts a second 

 apart are shown. 



current through its electromagnet (e.g. by means of the Brodie-Palmer 

 clock), there are three distinct ways (cf. fig. 3) in which it can be made to 

 notify the occurrence of something other than the closures of the seconds- 

 clock : (1) The rendering of these closures ineffective by opening the circuit 

 at some other point, an Unbroken abscissa being thus produced. This will 

 be called Signal 1. (2) The continuous closure of the chronograph-circuit 

 by means of a key " in parallel " with the clock-contact, the abscissa being 

 thus shifted in height, while seconds cease to be recorded This will 

 be called Signal 2. (3) Arranging that the clock-closures, instead of 

 magnetising the signal, demagnetise it, this being attained by continuous 

 closure of the chronograph-circuit as in (2), while at the same time the 

 clock-contact is made to act as short-circuit to the signal, the seconds-record 

 being thus inverted. This will be called Signal 3. 



The sharpness of Signal 1 is obviously less than that of Signal 2 in the 



