All About Engines

6 All About Engines What an engine of this kind looks like in reality will be gathered from Fig. 5, Plate 1, which shows the front view of one made by Marshall and Sons, of Gainsborough. In order to understand how it works we shall have to look inside it, and for that purpose we shall rely mainly on diagrams in which what is unneces- sary to the explanation is left out. Thus Fig. 6 shows a section through such an engine. For the sake of the reader who is not quite sure what “ a section ” means, it may be said that it is the view which would be obtained if the whole thing were cut through, and one of the cut faces were being looked at. Generally a section would be drawn to scale, so as to reproduce the exact proportions of the original engine before it was, in an imaginary sense, cut in two. This one is not drawn to scale. It is purely diagrammatic. It represents roughly the shape and general arrangement of the parts, but it does not show exactly their shapes or relative sizes. As each of the parts on the drawing is named, a very full written description will not be required. The cylinder is of cast iron, shaped like a barrel, with a box on the side called a steam chest, and it has covers bolted over each end and over the steam chest. The interior of the cylinder and steam chest are connected by narrow steam passages or “ ports,” and there is another opening between them by which steam can escape from the cylinder when it has done its work. This may lead to the open air or into a condenser ; but in this case it leads into the open