count of both convenience and good taste, to use but one color in painting a bridge. A proper choice of color, however, is a material advantage; and it is correct to vary the color in certain accessory portions of the structure, such as machinery-houses, the lettering on name-plates, etc. Some engineers have advocated painting the tension and compression members of different colors, but this would get one into difficulties in spans where certain strictly tension-members are made stiff. Ornamental figures should be painted of the same color as the rest of the bridge. In general, it may be stated that for ordinary conditions of landscape the heavier the structure the lighter should be the color of the paint used, for the reason that if a bridge has an appearance inclining toward clumsiness this objectionable effect can be lessened by reducing the prominence of its members; while, on the other hand, it bridge which is of such an extremely light and airy design as to produce an appearance of weakness can be made to look stronger by adopting a paint of dark color, and thus bringing its members into greater relief in respect to surrounding objects. With very dark backgrounds, however, it will often be advisable to use a light-colored paint even for slight structures, so as to give the bridge a definite outline.

In regard to the ornamentation of bridges by the adoption of elaborately artistic approaches, but little has yet been done in America, the reason being that any money so expended has evidently no utilitarian purpose, and consequently to the eye of the solely practical man appears to be entirely wasted. In Europe it is customary to ornament large and important bridges in this way; and the time is coming when it will be the practice in America also.

A proper proportioning of piers and abutments has a great deal to do with the obtaining of an artistically designed bridge; but, unfortunately, in these, even more than in the superstructure, the almighty dollar is generally the ruling influence in the design. In many bridges the piers do not seen to be massive enough for the spans ; and, as will be shown in Chapter XXII,  too often they are not sufficiently large to meet certain  important   engineering   requirements,  which  are,  as  a  rule,