THE STYLUS 65 



the transmitting cylinder double the size of that 

 used in the reception. 



The stylus consists essentially of a finely -pointed 

 needle, and ordinary gramophone needles set in 

 a suitable holder have been used with success ; the 

 best form of stylus is one originally designed by 

 Mr. Sanger Shepherd, and its form is indicated in 

 the diagram. The stylus, made of steel or other 

 suitable material, is of the shape shown, and has a 

 small tube put through it about the middle, which 

 acts as an axis. Two needle-point 

 bearings fit into this finely-drilled 

 tube, so that it is free to turn with 

 minimum friction ; one end of the 

 stylus is bent downwards and is 

 pointed sharply, the other has a hole through it to 

 which is attached a tension spring, so that the 

 pressure of the style on the cylinder can be regulated. 

 The sparking at the point of contact is apt, if not 

 sufficiently well overcome, to quickly blunt the stylus, 

 and Mr. Shepherd prepared several with iridium 

 points let into the steel " head " ; these proved very 

 satisfactory, but were eventually replaced by a 

 modification which was designed to facilitate the trial 

 of needles of various materials, working at different 

 angles to the surface of the drum. This design is 

 shown in Fig. 30. 



Here H is the head of the stylus, drilled so that a 

 needle AB can be fitted into it and clamped by the 



P.T. F 



