TOO MUCH PISTON CLEARANCE.
On one of our leading railroads a locomotive was rebuilt, and fitted with the extension smoke-box, which was an experiment for that road, and consequently was looked upon with some degree of distrust. When the engine was put on the road, it was found that it did not steam satisfactorily. Of course, it was at once concluded that the draught arrangements were to blame; and experiments were made, with the view of adjusting the flow of gases through the tubes to produce better results. The traveling engineer of the road had charge of the job, and he proceeded industriously to work at locating the trouble. He tried every thing in the way of adjusting the smoke-box attachments that could be thought of, but nothing that was done improved the steaming qualities of the engine. He then proceeded to search for trouble in some other direction. The result of his examination was the discovery that the engine was working with three-fourth inch clearance at each end of the cylinders. This, he naturally concluded, entailed a serious waste of steam; so he had the clearance reduced to one-fourth inch. When the engine got out after this change, it steamed very satisfactorily; and the extension smoke-box is no longer in disrepute on that road.