The physiological, pathological and therapeutical effects of compressed air / by Andrew H. Smith.

  • Smith, Andrew H. (Andrew Heermance), 1837-1910.
Date:
1886
Catalogue details

Licence: Public Domain Mark

Credit: The physiological, pathological and therapeutical effects of compressed air / by Andrew H. Smith. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    CHAPTER II. THE NEW YORK CAISSON. Before the St. Louis bridge was projected, a much more gigantic work had been inaugurated at New York, and plans and specifications had been adopted which anticipated the leading features of the work at St. Louis. To cross a stream i,6oo feet in width with a single span was an idea never before entertained. But the difficulties were immensely increased by the fact that the towers to support this immense structure had to be erected under circumstances that rendered the usual methods for sinking piers impracticable. It was, therefore, determined to employ the method by compressed air, and caissons were constructed having the horizontal dimensions of the proposed piers, which, on the New York side, were 102 by 172 feet. Each caisson was in effect a wooden box turned bottom up- ward, the interior space being 9 feet high. The roof of the New York caisson (bottom of the box) was 22 feet thick, of solid timber bolted together, and was supported by frames running from side to side, which frames, together with the edges of the box, were to sustain the vast superincumbent weight, aided by the upward pressure of the condensed air within the cais- son. The area of the structure was equal to seven building lots of 25x100 feet each. The caissons having been built on ways, were