Bell claims that this patent has certain new and useful improvements in Receivers for Electric Telegraphs. There is a reference to the patent 161,739 dated April 6, 1875 which is shown in the box on the map above. In this patent (161,739), Bell showed and described the working of the receiver which was put into vibration by electric impulses. The system consisted of a local circuit independent of the receiver and a vibratory circuit breaker within that local circuit. The receiver caused a permanent make of the circuit breaker when the receiver vibrated and a permanent break when it ceased to vibrate. The vibratory circuit breaker lever vibrated/oscillated at a slower rate than the receiver.
This * particular invention concentrates on the vibratory circuit breaker.
(Refer to Fig. 1)
In place of the oscillating lever employed before, Bell uses a spring arm/bar wh ich again vibrates at a slower rate than the receiver. The free end of this arm/ bar (i.e. the left end of the bar 'b') overlaps the vibratory portion of the re ceiver (i.e. the right end of 'a' in Fig 1). The distance separating the two is adjustable. The bar itself has a spring action. The distance between the bar an d the contact point 'f' is also adjustable. 'A' is an electromagnet. Its uncover ed leg is attached to the end of the vibratory reed or steel spring 'a'. Electri c impulses traversing along the wire magnetizes 'A' which then causes 'a' to vib rate. The vibratory circuit breaker is shown to the right of 'A'. The light spri ng arm 'b' is supported on 'c'. The distance between 'b' and 'a' can be varied b y moving the stem 'd' by means of the screw 'e'. The point of contact to complet e the local circuit is at 'f'. This point is adjustable by means of the binding nut 'h' which causes the 'f' to move up and down along the post 'g'. As mentio ned before, the rate of vibration of 'b' is less than that of 'a'. Consequently, a permanent loss of contact exists between 'b' and 'f' when 'a' is in vibration. When electric impulses cease, the bar 'b' serves t o dampen and instantly check the vibrations of 'a'.
(Refer to Fig. 2 and Fig. 3)
In Figs 2 and 3, 's' is a morse sounder or a register or some suitable apparatus . In Fig 2, 's' is deactivated whenever 'a' vibrates (shown in Fig 1, but not sh own in Fig 2 or 3) due to the loss of contact between 'b' and 'f' leading to the incompletion of the local circuit ?. In Fig 3, whenever 'a' vibrates, 's' is ac tivated because of the sole existence of the electric path from the positive ba ttery terminal to the negative terminal via the morse sounder. However, when 'a' ceases to vibrate, the battery terminals are short circuited via 'b' thereby de activating 's'. Bell claims that in Fig 3, the armature of 's' should be further away from the magnet, or should offer more resistance than in Fig 2. (WHY?!).
**** Bell claims that this invention is not only applicable to intermittent syst ems but also to undulatory systems described in his patent of March 7, 1876.