ON THE STRENGTH OF PILLARS. 
441 
Table VII. — Pillars enlarged in the middle, differing from the last only in having- 
discs upon the ends, two inches diameter, and half an inch thick, turned flat. 
Length 60| inches. Plate XV. No. 4, E, F. 
End diameter. 
Middle diameter. 
<+-« 
o 
.I? 
*3 
Mean weight of 
pillar. 
Deflection. 
Corresponding 
weight. 
Breaking weight. 
Mean breaking 
weight. 
Breaking weight 
of uniform pillars 
of same weight, 
with discs. 
Remarks. 
inch. 
inch. 
lbs. oz. 
lbs. oz. 
inch. 
lbs. 
lbs. 
lbs. 
lbs. 
1*04 
1 - 3 ] 
16 10 
•03 
4251 
The first of these pillars, with enlarged middle, broke 9| 
•05 
8171 
inches from the middle, and had both discs split. A 
• 0Q 
8955 
wedge breaking out, at the place of fracture, showed the 
depth of tension to that of compression as 104 : 16. 
•12 
9739 
The next pillar gave the ratio 104 : 22, breaking 7-J inches 
•17 
10525 
from the middle, as well as one end breaking off, and the 
•28 
11307 12091 
1 
disc at the other splitting. 
1-00 
1-27 
16 4 
16 10 
10915 
> 11526 
11756 
The third pillar broke 11 -6 inches from the middle, and 
1-03 
1-27 
17 ] 
11573 
/ 
had both discs split. The pillar, with enlarged middle, 
bore Lth less than the uniform pillar. 
1-06 
1-36 
21 13 
21 13 
•06 
13699 
■ 
This pillar, with enlarged middle, broke 7J inches from 
•07 
14459 
middle ; it bore g^jth part more than the uniform one. 
•12 
15803 
•16 
17147 
•29 
18491 
•50 
18939 
19163 
19163 
16924 
The strengths of the uniform disced pillars, of the same weight and length as those 
with enlarged middles, were calculated according to the assumption that the strength 
varied as the 1*77 5 power of the weight. See Art. 46. 
The first was obtained from a mean between the results of two experiments, where 
an uniform disced pillar of the same length, and 15 lbs. 14 oz. weight, was broken 
with 10831 lbs. ; and the second, from a like mean, in which a disced pillar of that 
length, and 21 lbs. 6^ oz. weight was broken with 16369 lbs. 
3 L 
MDCCCXL, 
