But, it may be said, if a steel-trussed bridge, economically and wisely constructed according to our present light, offends our ideals of grace and beauty, the fault perhaps is not in the structure, but in the rigidity and immobility of the ideals which have been established by conditions long since outgrown in the progress of science. The attempts of the English bridge-builders in iron in the early part of the century to meet these old ideas resulted in constructions which, though they may satisfy the eye of the artist, and combine more or less gracefully with the landscape, are uneconomical and unscientific. The principles of structure involved are incorrect, and unnecessary expense was incurred in forcing into the design features conventionally acceptable, but which had nothing to do with the structure, and which in fact were a hindrance to it, concealing rather than illustrating it.

The architect will not find it difficult to agree with his brother the engineer, that a mask of ornamental cast iron, covering the essential features of the structure in order to force upon it an effect of grace, is illogical in the extreme. Indeed, a great modern master of architecture has laid down the axiom: "A form which admits of no explanation, or which is mere caprice, cannot be beautiful; and in architecture, certainly, every form which is not inspired by the structure ought there fore to be rejected." The conscientious modern architect aims to shape his design according to this reasonable limitation, and he has been thereby enabled to produce occasional effects of beauty without imposing on his composition a single idea which is not suggested either by the structure or by the use of the building. Even a factory, a gasometer, a railway shed, an elevator, need not challenge the architect in vain to produce effects of fitness not entirely inconsistent with the requirements of art. Indeed, the engineer himself, with axioms or maxims of art, has, in the evolution of the roof-truss, the locomotive, and many industrial machines, succeeded in satisfying ideals of beauty in the very process of making them powerful, compact, and economical of material and space. The modern steel-armored war-ship has already, in this early stage of its rapid development, substituted for the ideas of maritime beauty, speed, and strength which prevailed in the time of Nelson and the other great historical admirals, and which were celebrated in the songs of Dibdin and Campbell, an entirely different ideal, hardly less imposing, though as yet without poetic recognition. But the evolution of the steel-trussed bridge has as yet satisfied neither old ideals of beauty, nor has it made new ideals. Its essential lines are drawn in apparent disregard or contempt for grace of outline or elegance of detail. The difficulty seems to be inherent in the present approved structural system of designing horizontal, straight, open-trussed girders or cantilevers, rest-

ing on rigid vertical piers of  masonry  or iron, without regard to any other considera-tions excepting those of statics. The eye requires to be satisfied as well as the trained intelligence, and demands not only grace of proportion, but a certain decorative emphasis  expressive of  especial   functions.    The primitive  post  and  lintel  structure of