When the several pieces above described are put together, the apparatus for opening and closing the valves and producing the cut-off is complete, as shown in fig. 72, and it operates as follows: 

[Illustration:  Fig. 71.]

[Illustration:  Fig. 72.]

Motion is communicated by gearing from the crank-shaft to the bevel wheel on the piece (d) on the end of the hub D, and is communicated to the spindle of the governor, which is screwed into the socket on D’.  As the balls rise or fall, through change of centrifugal force due to the variation in the speed of rotation, they raise or depress the governor-rod, which passes through the spindle and the hubs D’ and D, and is attached to the feathers, thereby raising or depressing the feathers, which, acting on their respective spiral grooves, instantly alters the lift of the cam on the shell (C), and brings the closing toe (t) on the shell (C’) into proper position for closing, and so regulates the amount of steam admitted to the cylinder.

[Illustration:  Fig. 71.]

Consequently, any speed may be selected at which the load of the engine is to move, and any variation from that will be instantly felt by the governor, and corrected by this simple and beautiful device.  There is no jar in the working of the parts; the feathers move noiselessly in their grooves; the governor rod moves up and down through the spindle and the hubs D and D’, and can be regulated by hand to give any required opening of the steam ports to suit the work to be done.  Any change in the amount of work will then alter the speed of the engine, and so affect the governor and cam, as before said.

It is unnecessary to insist on the great economy attained by using steam with a well-regulated cut-off, for practical men know now that the essential points of excellence in the steam engine are a good boiler, which generates the greatest quantity of steam for the least consumption of fuel; and, secondly, a reliable cut-off, which uses the steam to the best advantage, by admitting the proper quantity for the work required.

STEAM FIRE ENGINES.—­Portable engines for the extinguishment of fires, are an American invention, and to Messrs. A.B. & E. Latta, of Cincinnati, working on the right principles, is due the credit which they claim in their circular, as follows: 

“We claim to be the original and first projectors of the first successful steam fire engine in the world’s history.  There have been many attempts at making a machine of such construction as would answer to extinguish fires; but none of them proved to be available in a sufficiently short space of time to warrant their use as a fire apparatus.  We hold that a steam fire engine should be of such nature as to be brought into requisition in as short a space of time as is necessary to get the machine on the ground, and the