Compressed Air Work And Diving 1909

RS4ST RIVER TUNNELS. 95 the shiekl then movecl forward, the floors all the time remaining stationary, and supporting the rock face. These lloors were also very useful in oiving- standinp- room for the rock drills, and allowing them to be set up in the most favourable position. There were two hydraulic erectors of the ordinary type at the back of the shield, worked by a rack and pinion. The shielcls were fitted with air pipes so that air coulcl be admitted separately to each compartment, but for most of the time it was not found necessary to do this, and the end of the inlet air main was kept about 30 ft. behincl the shiekl. Diere were three boiler-shaped locks in each bulk- heacl, the emergency lock at the top, and two others below, which could be usecl for either men or material. These bulkheads were built of concrete. A travelling platform, similar to the one at the Blackwall Tunnel (see Plate III.), was usecl for tighten- ing up the bolts from, grouting, and caulking. Eight medical locks were provided, four each side the river, for treatment of decompression symptoms (Fig. 15B). Each contained two bunks for the patients, and one end was divided off to form an entrance chamber, so that a cloctor could enter at any moment to attend a 1 ' lowcnn0 the pressure. A fresh patient coulcl also be introckiced at any time during the treatment of another. The locks were warmed with electric heaters, and a telephone was fitted so that the patient coulcl com- municate with persons outside. In this connection it is interesting to note that medical locks were first usecl for the treatment of decompression cases by A'Ir ]\Ioir durin”' the clriving of the first tunnel in New York under the Hudson River.