ON THE STEENGTH OF PILLAES OF CAST lEON. 
873 
Tables III., IV. and VII. give both the direct and transverse strength of the pillars to 
which the preceding remarks are applicable. 
The following summary contains the results of the experiments in Tables II. to VI. 
upon solid pillars varying in length from 10 feet to 7 feet 6 inches, 6 feet 3 inches, and 
5 feet, or as 8, 6, 5, 4, all from models 2^ inches diameter ; the results are from thir- 
teen kinds of cast iron, as before, or from twenty-six pillars 10 feet long, eleven pillars 
7 feet 6 inches long, six 6 feet 3 inches long, and three 5 feet long, forty-six pillars in all. 
This does not include pillars round at the ends, and others cast I^ inch diameter. 
The mean crashing strength of short pillars of the irons, cast 2^ inches diameter, is 
175 '7 tons. The other mean values are as below: — 
j Length. 
Breaking weight. 
Ultimate decrement 
of length. 
Ultimate deflection. 
Ratio of breaking weight 
to crushing weight. 
tons. 
in. 
in. 
10 ft. 
23-27 
-176 
-75 
-146 
7 ft. 6 in. 
40-57 
-235 
-66 
•231 
6 ft. 3 in. 
51-77 
-248 
•294 
1 5 ft. 
57-69* 
-296* 
-57* 
•472* 
whence it appears that the ultimate decrement of length is inversely as the length 
nearly. Another object of these experiments, and of others on pillars of smaller dia- 
meter in Tables III. and V., was to determine the powers of the diameter and length 
on which the strength of pillars depends (see pp. 865 and 866). 
* From two experiments only. 
Third Summary. 
