Harlan F. Stone

“ The adaptation independently made by engineers and builders of these familiar appliances to the movement and distribution of concrete cement in building operations and the independent patent applications, within a comparatively short space of time, for devices for that purpose are in themselves persuasive evidence that this use, in combination of well known mechanical elements was the product only of ordinary mechanical or engineering skill and not of inventive genius. ”

“ That the combination embodied in the described apparatus produces a useful result in the mechanical arts, and in modified form is widely used in building operations, is established. Our inquiry, therefore, must be addressed to the question whether the combination is novel, and whether it passes the line, sometimes tenuous and difficult of ascertainment, which separates mechanical skill from invention. The pursuit of this inquiry involves a consideration of the state of the art prior to Callahan's application, of which elaborate proof was made in the trial court. ”

“ The apparatus described in the letters patent is capable of use in conveying 'wet' or 'mush' concrete from the point where it is prepared for use and distributing it to points where it is incorporated into a building in process of construction. When the mixed concrete is in readiness to be placed in the forms or molds in which it is allowed to 'set' or harden into an integral part of the structure, it is elevated by the 'raising means,' usually a bucket, skip, or other suitable conveyor, to the 'receiving means,' a hopper, in which the concrete is deposited. ”