The riveting of the frames and beams is the simplest of all the work overtaken by the hydraulic riveters, and it is here the system is seen to most advantage. In any yard furnished with these machines rivets are closed at a greatly accelerated rate compared with work done by hand. Tweddell machines have been known to close, in beams, 1,800 to 1,900 rivets per machine per day of 9½ hours. In frames the average rate at which rivets are closed is about 1,400 per day. The cost for this section of riveted work has been computed to be about one-half of that by hand, and the quality of the work is everywhere acknowledged to be better. With the same number of men the work is accomplished in something like one-third of the time. The _modus operandi_ in overtaking this feature of the work may be briefly described. For the riveting of the frames, in almost every case, two cranes of any convenient construction are fixed at the head of the berth in which the vessel is to be built; the frames are laid across the keel as in hand work, and rest on trestles, where the portable riveter, carried on the before-mentioned cranes, rivets them up. As the riveting in each frame is completed it is drawn down the keel by steam or hand power, and set up in place. The riveting of the beams is a still more simple operation, the beam to be riveted being placed under a gantry somewhat longer than the beam itself, and upon which the portable riveter travels. The suspending gear in this and other of the Tweddell machines combines the functions of hydraulic lifts for raising or lowering the riveter, and of conveying the necessary hydraulic pressure to the riveter. The beam is supported on trestles, and the riveter, having the facilities for travel and exact adjustment just described, accomplishes the surprising work before mentioned.