so. Had more attention been paid to first principles of design when the plans for most of the New York and Brooklyn elevated railroads were being prepared, millions of dollars would have been saved. This statement can be verified by a perusal of the author's paper on Elevated Railroads, referred to and quoted from in Chapter VIII, more especially the resume of the discussions and Mr. Hedrick's report on the said New York and Brooklyn elevated railroads.

In spite of all the care that the most expert designer call give to his work, errors of greater or less magnitude will creep in occasionally; and one can always improve somewhat upon any finished design. Such being the case, it follows that the designing of steel structures should be intrusted to expert and disinterested designers only, instead of, as is generally the case, to the cheap draftsmen employed by the manufacturing companies.

There are a few features of the specifications given in Chapters XIV. and XVIII. which will require a little explanation or comment. This will be given in this chapter, the various items being treated, as nearly as may be, in the order in which they occur in the said specifications.

"A" Truss Bridges

This style of structure, originated by the author and covered by letters patent, is a four-panel truss-bridge having eye-bars in bottom chords and centre verticals, and rigid members for all the other portions of the trusses and for the entire lateral system. It was evolved in this way: For a number of years the author was dissatisfied with all railroad bridges for spans between the superior limit of the plate-girder and a length of about one hundred and fifty feet, ordinary pin-connected, through, Pratt trusses being too light and vibratory, and the riveted bridges as then built being clumsy, unscientific, and uneconomical. On this account he tried for some time to find an opportunity to experiment upon a design of his own to fill a portion of the gap, but the opportunity did not occur until April 1893,  when  he  was  retained  by the General  Manager of