Every change in the construction, alteration in the proportions, or addition to the attachments of locomotives is a subject of intense interest to the men and a topic of endless discussion at all times and places. The theories which are propounded, and the yarns which are spun while sitting around hot stoves in round-houses, or waiting for passing trains on side-tracks, would fill many books. Jack never tires of telling what his engine did when "she was going up Rattlesnake Grade," and Smoky Bill grows excited when he describes how Ninety-six turned her wheels in making up forty-nine minutes time in the down run with the "electric express." Locomotive engineers and firemen read with avidity everything which is explanatory of the construction or working of locomotives, but generally have a contempt for things which have no practical bearing. They demand "lucidity" in what they read with as much vehemence as Matthew Arnold did, and some editors and college professors, whose writing and thinking are foggy, would be greatly benefited by the criticisms of the Locomotive Brotherhood. [Illustration: Fig. 38.--Interior of Erecting Shop, Showing Locomotive Lifted by Travelling Crane.] Much might be written about the duties of locomotive-runners and firemen, and the qualifications required. It is the general opinion of locomotive superintendents that it is not essential that the men who run locomotives should be good mechanics. The best runners or engineers are those who have been trained while young as firemen on locomotives. Brunel, the distinguished civil engineer, said that he never would trust himself to run a locomotive because he was sure to think of some problem relating to his profession which would distract his attention from the engine. It is probably a similar reason which sometimes unfits good mechanics for being good locomotive-runners. [Illustration: Fig. 39.--Forging a Locomotive Frame.]