A closely-fitting adjustable piston is provided at one end.
The magnet between the poles of which the rectangular signal coil moves is built up of a number of thin flat horseshoe-shaped permanent magnets of a special quality of steel, and is provided with adjustable pole pieces.
The beam must be provided with a small ball of metal which can be screwed up and down a stem on the top of the beam for the purpose of accurately adjusting the position of the centre of gravity, and there should be a small adjustable weight on a fine screw projecting horizontally from one end of the beam for the purpose of accurately balancing the arms.
Finally, I invented a new Adjustable Post-hole, which I thought would make my fortune.
On arriving at a certain height the lift ceases and the jenny is released, and by the continued pull of the rope, it runs up the jib; on arriving at an adjustable stop, the jenny is again locked, and the load can be lowered out; the hook can then be raised, when the jenny is automatically unlocked, and on paying out the rope the jenny gravitates to its first position, when the load is lowered and the cycle repeated.