road bridges. The author saw an elevated railroad in Kansas City removed practically for this cause alone, the pins having been cut into and the eyes elongated as much as an eighth of an inch. In the author's opinion, a steam-railroad-bridge span should be pretty long before pin-connections are resorted to—say 500 feet for simple spans and 900 feet for the main openings of cantilevers; but for highway and electric-railway bridges these lengths may be cut down from twenty-five to thirty-five per cent. The point is one to be settled by individual judgment based upon experience—not prejudice. The size of the appropriation available for construction may quite legitimately be a ruling factor in making the decision, because a pin-connected highway span of five hundred, or even four hundred feet, does not make a bad bridge; although, if the traffic be great, such a structure certainly is inferior to a riveted one, in that it will vibrate more and will possibly be shorter lived. But if the live load assumed for the designing be never greatly exceeded, and if the structure be always kept properly painted, it would probably require more than a century of use to wear the pins and pin holes to any dangerous extent.

The discovery of a high-alloy of steel that can be manufactured at reasonable cost, and the development of a satisfactory and absolutely-reliable method of heat treatment thereof for eye-bars may bring the pin-connected structure once more into vogue; but it will be for long spans only, and preferably for highway structures.