The Montgomery advertiser., 1904-01-13

Roman engineers were the first to rec | ognize It's value and to develop it as the | most important of all bridge building
 principles. The beauty of its curved out I line was so early recognized, however, ! that the ancient Greeks used the effect
 in many of their structures without ap-
 plying the principle of horizontal thrust
 that makes the true arch.''
 This principle, which underlies so mcuh | of modern architecture as well as bridge ! building, is nevertheless very simple and Is very well represented by the old Hin ! doc saying. The arch literally never sleeps, for it's efficiency lies wholly fin the | constant pushing exerted by each block of building material upon Its neighbor.
 this outward pressure starting from the keystone or central block of material and being communicated to each succeeding section until it is finally met by the re- sistance of the solid foundation upon which the last section rests. The bridge builder, therefore, may have to penetrate far below the surface of the earth or the bottom of a river before he begins to build up his arches and as a matter of fact the volume of masonry that is coy- cred up and out of sight is not infre- quently greater than what is visible
 Every stone in a true arch is link in the chain which transmits and supports the downward pressure of whatever weight of material or of humanity may be placed above it. It's construction nat uralIy demands a thorough knowledge of the method of preparing firm founda- tion and both the ancient Hindoos and Egyptians, lacking complete confidence in their knowledge of this important factor in arch construction, argued that the sleepless thrust of the arch might easily become force slowly tearing it to pieces, and used the arch very sparingIy indeed in consequence.
 The modern Brother of the Bridge' learns more about foundations than even the ancient Romans. many of whose bridges are still standing and likely. with proper caretaking. to outlast many fu- ture centuries, and he knows also more about testing his material during the process of construction. Just how these ancient bridge builders got their prelim- mary training is unknown but 1t is an interesting fact that in later period both Leonardo da Vinci and Michael Angelo were practical engineers as well as art ists. The modern bridge builder on the other hand is invariably the product of technological instruction, the first school of engineering having been established in France in 1760 when an old French drawing school became the "Ecole des Fonts ct Chaussees' and was put in charge of the noted contemporary engi- neer Perronet. Since that time the greater part of the public works of France have been built by graduates of that school, just as many of the impor- tant engineering problems of America are now in the hands of graduates of the Massachusetts Institute of Technology or those of Germany are under the super vision of men who got their training at Charlottenberg.
 Perhaps the most interesting minor fact about these mighty structures, with their series of graceful arches, is that the man who designs them must be able to see the finished bridge in all its perfection by an effort of the imagination based upon geometrical drawings of the different parts. At the Institute for example the future bridge builders have access to a group of models illustrating the different kinds of arches and other forms of bridges with which they must become fla miliar, but these models are very little used fin instruction The student is taught to visualize" his completed bridge from the moment when his plans begin to take form on paper, and he must not only nIan the shape and dimensions of every
 block of stone that goes to make his arch
 but he must be able, eventually. to feel almost by instinct how the proportions Of the arch will look when actually com
 pleted. And this planning of the actual
 bridge is only one part of his education