the use of power riveters. This is especially applicable to box sections with the flanges of channels turned in. In general, the clear distance in such cases should be not less than 5 1/2" or 6".

"Avoid sections calling for the use of a variety of sizes of shop and field rivets in the same span or structure.

"For narrow, ' I '-shaped sections, preference should be given to four angles with a web plate instead of four angles laced. Often for such narrow sections the latticed type accomplishes very little or no saving in weight, and the shop expense is greater and the result is less desirable from a maintenance standpoint, as compared with the plate-and-four-angle section.

"Quite often a small increase in the thickness of stringer webs will eliminate the necessity for the use of stiffeners.

"Designers very often do not make enough allowance between gross and net section for the proper maintenance of the latter and at the same time for the preservation of rational details at the critical points. For instance, according to the 1920 specifications of the American Railway Engineering Association, if only one 7/8" rivet hole is allowed out of an angle, the stagger must be four inches; and other specifications have been more stringent. If the piece happens to be a 6" X 4" angle with two rows of rivets in the six-inch leg, the detailer is in trouble at once with the location of rivets in the four-inch leg adjacent to the critical section. He is often compelled to give it up and encroach on net section after he has wasted a lot of valuable time in trying to meet the conditions. Any angle with punching in both legs, used in tension, should have two rivet holes deducted from the gross section.

"In plate-girder work, fillers under stiffener angles should not be required to fit tight against flanges. The overrun in width of flange angles, often varying for the different angles on a single girder, means the re-cutting and fitting of fillers to suit. This results in a slowing down and an increased cost in the work of fitting up the girder for riveting. A clearance of at least 1/8" should be permitted at each end of filler.

"All unnecessary bevel cuts on the ends of long angles, plates, or other shapes should be dispensed with. These are much more expensive to make on long pieces than on small detail parts. It seems somewhat absurd carefully to cut the end of an angle to bevel, for the sake of appearance, when it is not exposed to view in the finished structure. Indeed, the aesthetic value of such bevel cuts is very much in question, except where a projecting corner is exposed to the skyline.

"The ends of columns for viaducts or other structures resting on masonry can often be made less expensive in both weight and workmanship by using thicker base plates and omitting vertical stiffening angles with their extensive arrangement of wing-plates that are intended to help in the distribution of the load.

"Finally, and in general, the designer should give the most careful atten-