SHOP-PRACTICE AND ERECTION. 283 



With the second and succeeding rings, a short " gin- 

 pole " is first bolted to the top rivet-holes of the section 

 below, and sheets are hoisted in succession and temporarily 

 fastened with bolts until the entire circle has been so placed, 

 when riveting is begun, the heating-forge being conveniently 

 located in a travelling-carriage or " cage," moving along the 

 circumference upon small rollers or trolleys as required, 

 while the riveter, forming the field-heads with a. forming- 

 hammer, upon the head of which two men strike with 

 sledges, remains upon the inside of the structure, all the 

 workmen standing upon scaffolding, which is raised as the 

 work proceeds, and which may consist of 2" X 2" uprights. 



Upon the completion of the metal-work of the shell, the 

 ornamental cresting or cover, the ladders and other fittings 

 and trimmings are put in position; the tank then being ready 

 for testing, is filled with water. Leaks along the seams are 

 caulked carefully, but no caulking should be permitted upon 

 leaks about rivet-heads, due to imperfectly-filled rivet-holes 

 or loose rivets. Such rivets should be cut out with chisel 

 and sledge; the hole reamed out and larger rivets driven. 

 Such leaks are carefully marked while the water is in the 

 tank and the repairs made after the vessel is emptied. No 

 caulking or chipping should be allowed while the water re- 

 mains in the tank. The hoisting of plates is usually done by 

 hand, using a winch, from which a line passes through a block 

 hung from a loop or hook on the " gin-pole," and to which 

 is attached some form of tongs or " grab," which may be 

 hooked into the rivet-holes of the sheet to be hoisted. A 

 " riveting crew," or gang, consists usually of a foreman, 

 who also personally does the caulking of seams; a riveter, 

 generally an experienced boiler-maker; a skilful " heater," 

 who heats the rivets to a forging heat and passes them in 

 tongs into the rivet-holes, and three laborers, one of whom 

 directs a heavy suspended weight against the rivet being 



