SPECIAL REPORT OF MR. HILL, ON MACHINERY. 423
the face-plate, so that a larger swing can be had when the tool is desired for facing. When not wanted for this purpose, the gap is tilled with a block, which slides in, having upon it a continuation of the ways. Gears are not cut, even on the best tools of the makers of highest reputation, on the theory that the outer scale is the best portion to resist wear. The working-handles about the machines are of horn, turning loose upon their centres. Planers are much more universally built with double heads than with us, even those of comparatively small size. Those in the Exposition were also universally fitted with a cord, or other arrangement, for mechanically lifting the tool so as to clear its point in running the platen back. Many tools for slotdrilling were exhibited, and this appears to be a tool in much more general use than with us, in European shops.
Overhead travelling-cranes were in use in the Exposition, and the whole work of removing the exhibits, to and from the cars which brought them, was done with these. The writer found, also, the new and well-arranged machine-shops, in England at least, generally fitted up in this way. The cranes were largely used also in foundries and in lumberyards, and universally in the freight-yards of railways. As is generally known, these travelling cranes consist of two parallel rails supported overhead on walls or piers from forty to sixty feet apart, on which travels a truck. This truck is composed of two beams with wheels under the ends on which another truck traverses from one side to the other. This last truck carries the hoisting apparatus. Most commonly they were driven by a high speed hide-cord, passing through them from one end of the building and so arranged as to give all the motions through friction-gears at will.
Very fine examples of the material for conveying pow r er by wire-rope were also on exhibition, with plans of localities where the same has been applied. A set of wheels were shown of over twenty feet diameter, with the rope used. This form of conveying power, which is admirably adapted to the purposes of water-power, has not received the attention in New England which it deserves. It is largely used in Europe, and from 50 to 500 horse-power is conveyed to distances of nearly a mile. In some cases smaller powers are led off in various directions