154 TOWERS AND TANKS FOR WATER-WORKS. 



a problem, but have come to the conclusion that the joint, as 

 illustrated and described, for efficiency and freedom from 

 leaks, is best. I will say here that a joint of this descrip- 

 tion was carefully made and tested on the Emery machine at 

 the United States Arsenal at Watertown, Mass. The result 

 of the test was two-twentieths of I per cent, of the calculation 

 made, and the line of fracture was through the net section of 

 plate at the outer row of rivets, as we had predicted." 



Since the lecture delivered by Mr. Allen, in 1891, there has 

 been rapid progress both in the manufacture and use of steel 

 for structural purposes, and the practice of uniting steel plates 

 with steel rivets has become the rule rather than the excep- 

 tion, although it seems that the great majority of metal- 

 workers continue to be very conservative in assuming higher 

 shearing-values for steel rivets, and while the steel rivet is used, 

 calculations are made upon its efficiency without assuming 

 much higher values than it has been the practice to give to 

 iron rivets subject to shear. 



In 1896 the United States Government made a series of 

 tests upon riveted joints at the Watertown Arsenal. These 

 experiments were made on joints formed of steel plate, and 

 both iron and steel rivets. 



An investigation of the reports shows the average shear- 

 ing-value of steel rivets to have run as high as 55,000 Ibs. 

 per square inch for rivets of f-in. and {-in. diameters, and 

 about 45,000 Ibs. for steel bolts under the same condi- 

 tions. 



From these tests it would seem that the shearing-value of 

 rivets in single-shear was about the same as the ultimate 

 strength of steel rods under tension; and it would therefore 

 seem that a higher working value for rivets might be estab- 

 lished, and that for rivets in single-shear an ultimate value of 

 45,000 to 50,000 Ibs. per square inch of metal would not be 

 radical or likely to prove unsafe. 



