When the captain of a large steamer stands on the top of the pilot house and signals the engineer to go ahead or back, he has no means of knowing whether his order has been properly interpreted until the ship begins to move, and then, if the order had been misunderstood, it is often too late to avoid an accident. In order to let the captain know instantly which direction the engine is moving, Harry W. Granger has invented a contrivance which consists of a dial on the pilot house connected with the engine room by a common speaking tube, at the end of which is a bellows connected with shaft of the engine in such a manner that it sucks the air out of the tube when the engine goes in one direction, and blows it in when it moves the other way, thus operating an indicator on the dial. In order that the machine may be useful at night, when the captain cannot see the dial, reeds are so arranged so that when the engine goes ahead a high note is sounded and when it moves backwards a low sound is made.

This machine will be in operation on one of the largest steamers on the lakes.