"Inside forms for the shell were handled from "n" (shaped) tracks suspended from the cross-struts and were placed as soon as the steel had been put in.

"The pouring of the shell was done in alternate 80 foot (42 metre) sections. A good deal of difficulty had been anticipated in making a good job of casting this thin member, and the inside forms first provided had removable panels of doors so that the lower part could be poured from near the bottom. It was found, however, that if a sufficiently fine aggregate were used and the mixture kept very wet, little or no difficulty was experienced, and the doors were abandoned as unnecessary. The secret of success was found to lie in pouring batches alternately from each side, and in rapid work, thus insuring a constant backward and forward movement of the fluid concrete cross ways of the shell until it was full. This method made certain that the reinforcement was well surrounded and that no voids were left unfilled. This was only possible because the running foot quantities were small and a whole section could be cast in a short time before the concrete first poured could take its initial set.

"It was found in building the experimental section that the shrinkage in setting lifted the concrete off the outside forms. This had been expected, and the inside forms had been stripped as soon as the concrete was sufficiently hard to stand alone on the steep side slopes. The same thing was anticipated in building the aqueduct, and to prevent possible cracking from this cause, the inside forms were stripped within a few hours of pouring."