146 TOWERS AND TANKS FOR WATER-WORKS. 



make a tight joint, and they thought that if they pitched the 

 rivets wider it would' be difficult to caulk the joint so that it 

 would be steam- and water-tight. 



One would quite naturally assume that steel plates should 

 be riveted with steel rivets, but such is not the usual prac- 

 tice. Most of the boilers now constructed in this country are 

 made of steel plates, and they are largely riveted with iron 

 rivets. In this country there have been comparatively few 

 experiments on the strength of riveted joints made of steel 

 plates and steel rivets, and as the general practice is to use 

 iron rivets with both iron and steel plates, I confine myself 

 here to the discussion of the iron rivet. I will say, however, 

 that in England very careful experiments have been made, 

 and a large percentage of strength is given to steel rivets over 

 iron rivets. When the true value of the steel rivet is fully 

 decided, and its use becomes general in this country, that 

 value can be easily substituted for the value of iron rivets in 

 the calculations of the strength of riveted joints, the other 

 elements of the problem remaining the same. 



What value, then, shall we give to the iron rivets when 

 used in connection with steel or iron plates? In settling this 

 question, I have not only been aided by the experiments of 

 English engineers, but I have availed myself of experiments 

 made on the large Emery testing-machine at the U. S. Ar- 

 senal at Watertown, Mass. These experiments have been 

 made with American iron and steel, and hence will be valu- 

 able to us all in our practical work in this country. In a 

 series of five experiments with steel plates and iron rivets, 

 holes punched, the shearing-resistance per square inch was as 

 follows: 39,740 Ibs., 38,190 Ibs., 36,770 Ibs., 38,638 Ibs., 

 and 41,100 Ibs. In view of these results, and other similar 

 experiments, I assume 38,000 Ibs. per square inch as the safe 

 estimate of the single shearing-resistance of iron rivets in 

 steel plates. Later experiments may change these figures 



