Page:The Steam Turbine.djvu/64

 the old, consists of a high pressure and a low pressure turbine, each driving a pinion at 1,400 revolutions, gearing into a spur wheel on the screw shaft making 70 revolutions per minute (page 52). The gearing is entirely enclosed in a casing, and is continually sprayed with oil by a pump.

It is interesting to compare the working of the new and the old machinery. The appended diagram (Fig. 48) shows the comparative water consumption with reciprocating and turbine engines. Everyone who has experienced a rough sea in a screw vessel knows the disagreeable sensation of the racing of the engines whenever the screw comes out of the water. In the turbine vessel nothing of the kind occurs, and the reason is very simple. It is because of the great angular momentum of turbines, which is about 50 times that of ordinary engines, consequently they gather speed so slowly that before they have appreciably accelerated the screw is down again in the water. Ordinary engines often accelerate up to