I am a little piece of mechanism, attached to the upper extremity of the great connecting rod of the main shaft of a steam vessel. On the other end of the same shaft is fixed a crank, and to this crank is attached a rod, which goes down to the lower deck, and connects with the regulating part of the machinery of the same shaft. On the upper deck is a lever, which comes from the same rod, and serves to communicate motion to the indicator, which shows how the speed of the shaft is affected out of doors. On the inside of the ship, there is a long line of communications, running parallel with the shaft, as far as the cockpit, and an arm attached to the same rod serves to connect them together. On the lower deck is a square head,
