SHOP-PRACTICE AND ERECTION. 



285. 



fined entirely to panel-points or points of connection, all 

 other rivet-work having previously been done at the shop. 



The first panel having been secured, a smaller gin-pole 

 is bolted to each of the columns or legs in succession, and the 

 next vertical member is raised to its place and fastened by 

 bolts until all of the column-sections are so located, when the 

 horizontal and diagonal members are hoisted into position 

 and secured. When the last or upper panel is in place, where 

 the structure is surmounted with a platform, this is erected, 

 from which work conveniently proceeds upon the girders, 

 bottom, and subsequent tank-sections or rings, as has been 

 described. 



An approximate cost of such work is $25.00 per ton of 

 material, varying with the local conditions at the point of 

 erection. 



Field- rivet ing and Machine-driven Rivets. As the field- 

 work consists largely of riveting the members together, 

 the following, taken from the Locomotive, a paper pub- 

 lished by the Hartford Steam-boiler Inspection and Insur- 

 ance Company, may be of interest: " The driving of rivets 

 is such a comparatively simple operation, that it might be 

 supposed that it would be almost always well done. This is 

 far from being the fact, however, and bad riveting is one of 

 the commonest defects reported by our inspectors. 



' The rivets may be too short, or too long, or too small; 

 they may have heads that are too flat, or they may have pro- 

 jecting ' fins/ or they may not fill the holes, or the holes may 

 not come ' fair ' with one another. There are many ways 

 in which riveting may be bad. . . ." In reporting a particu- 

 lar case of imperfect rivet-work in the same article, is the fol- 

 lowing: " The inspector found the rivets * driven very low r 

 that is, the heads were entirely too flat. He had a num- 

 ber of these rivets taken out, and found that the holes in the 

 two sheets did not come opposite one another fairly. This 



