All About Engines

Engines for Ships 277 Mauretania requires 1,000 tons. But before con- sidering modern marine engines, let us glance at the changes which have taken place in their form since the Clermont and the Comet clove the waters of the Hudson and the Clyde. The Evolution of the Marine Engine The first satisfactory engine, it will be remem- bered, was a pump, in which the pump shaft was operated by a beam. When Watt adapted his engine for rotary motion he still retained the beam, and the early builders of marine engines followed his example. But as the beam took up a lot of room they soon began to fix it low down at the side. Long connecting rods from the cross head were pinned to one end of the beams, and the other end operated the cranks on the paddle-wheel shaft through short connecting rods. This side-beam engine persisted for a consider- able time. Another type peculiarly adapted for paddle boats was the oscillating cylinder, invented by Murdoch. This in its single-acting form will be familiar to every boy who has received a cheap model engine as a birthday or Christmas gift. The cylinder is pivoted to a block through which two holes are bored. One of these holes is connected with the boiler through the steam pipe, and the other leads to the air or to a condenser. As the crank shaft turns, the cylinder swings about the pivot, and a hole leading into the upper end of it is brought alternately opposite to the steam and exhaust ports in the block. Steam is there-