INTO THE STRENGTH OF WROUGHT-IRON PLATES. 
699 
General summary of Results as obtained from the foregoing Experiments. 
Cohesive strength of 
plates. Breaking 
weight in lbs. per 
square inch. 
Strength of single- 
riveted joints of equal 
section to the plates, 
taken through the hne 
of rivets. Breaking 
weight in lbs. per 
square inch. 
Strength of double- 
riveted joints of equal 
section to the plates, 
taken through the hne 
of rivets. Breaking 
weight in lbs. per 
square inch. 
57,724 
45,743 
52,352 
61,579 
36,606 
48,821 
58,322 
43,141 
58,286 
50,983 
43,515 
54,594 
51,130 
40,249 
53,879 
49,281 
43,805 
47,062 
44,715 
37,161 
53,879 
Mean ... 
52,486 
41,590 
53,635 
The relative strengths will therefore be, — 
For the plate 1000 
Double-riveted joint 1021 
Single-riveted joint 791 
From the above, it will be seen that the single-riveted joints have lost one-fifth of 
the actual strength of the plates, whilst the double-riveted have retained their resist- 
ing powers unimpaired. These are important and convincing proofs of the superior 
value of the double joint, and in all cases where strength is required this description 
of joint should never be omitted. 
On referring to the experiments contained in the separate tables, there will be 
found a striking coincidence in the facts tending to establish the principle of double 
riveting as superior in every respect to the general practice now in use of the single 
rivets. It appears, when plates are riveted in this manner, that the strength of the 
joints is to the strength of the plates of equal sections of metal as the numbers, — 
1000 : 1021 and 791*. 
In a former analysis it was 1000 : 933 and 731, 
which gives us a mean of 1000 : 977 and 761 
which in practice we may safely assume as the correct value of each. Exclusive of 
this difference, we must however deduct 30 per cent, for the loss of metal actually 
punched out for the reception of the rivets, and the absolute strength of the plates 
will then be, to that of the riveted joints, as the numbers 100, 68 and 46. In some 
cases, where the rivets are wider apart, the loss sustained is however not so great ; 
* The cause of the increase of strength in the double-riveted plates may be attributed to the riveted speci- 
mens being made from the best iron, whereas the mean strength of the plates is taken from all the irons expe- 
rimented upon, some of inferior quality, which will account for the high value of the double-riveted joint. In 
ordinary cases and in practice it will therefore be safer to take the mean of the whole, viz. — 
Strength of plates 100 
Strength of double-riveting 97 
And of single-riveting 76 
4 u 2 
