ON THE STRENGTH OF PILLARS. 
449 
Table XI. — Pillars of various forms and different modes of placing-. 
OJ 
H C 
. o 
®.s 
6 u 
2 
i. 
Description of pillar (all being cast from the same iron 
as before). 
Deflection. 
Weight 
producing 
the de- 
flection. 
Breaking 
weight. 
Remarks. 
Round hollow pillar, regularly tapering from 
the middle to the ends, like the frustums ot 
two cones, whose bases joined in the middle ol 
the pillar. Plate XV. No. 9, C, where the ex- 
ternal diameter was 2'24 inches, and the internal 
1*63 inch. The extreme diameter near the end 
was 1'73 inch; the length of the pillar 7 ft. 6| 
inches, and its weight 36 lbs. It had strong 
discs at the ends, 2£ inches diameter, turned 
flat ; hut was cast to be everywhere else of uni- 
form thickness. 
inch. 
•04 
•07 
•17 
•18 
•34 
•54 
lbs. 
4135 
10855 
21219 
after 
hanging 
one 
hour. 
25139 
27099 
lbs. 
28667 
It broke in five parts ; and 11 inches from the 
middle, and near the disc at each end ; the 
fracture seeming to have taken place first near 
the middle. The thickness of the metal at the 
place nearest to the middle was •33+'25 = -58 
inch; and at the other near to it •33-j- - 26=-59 
inch. At this last place a wedge broke out, 
which showed the compressed part to be -j^th 
of the diameter. 
2. 
Round hollow pillar from the same model as 
the last. 
External diameter in middle 2'24 inches. 
External diameter near to the ends l - 73 inch. 
Length of pillar 7 ft. 6J inches. 
Weight of pillar 36J lbs. Plate XV. No. 9, D. 
bent. 
•03 
•15 
•35 
•65 
3603 
12105 
21219 
25139 
27099 
27491 
It broke eighteen inches, and twenty-five inches, 
from the middle at the same end, and atthe disc 
at that end. A wedge broke out which showed 
the compressed part to be J^th of the diameter. 
The thickness of the metal at the place of frac- 
ture nearest to the middle was *19 -f ’34 = -53 
inch ; and in another place "34 -j- "25 = -59. 
3. 
Round hollow pillar, regularly tapering from 
the bottom to the top ; as the frustum of a 
hollow cone. Plate XV. No. 9, A or B. 
External diameter at bottom 2-22 inches. 
External diameter at top l - 70 inch. 
Internal diameter at bottom 1-61 inch. 
Length of pillar 7 ft. 6J inches. 
Weight of pillar 39 lbs. 
Its ends were turned flat, and it had a strong 
disc upon the top of double the diameter there, 
all the rest was cast to be of uniform thickness. 
bent. 
•02 
•12 
•22 
•30 
•42 
•60 
•87 
3355 
12403 
21857 
25917 
28353 
29977 
31601 
32413 
32413 
It broke about two inches below the middle, 
with the last weight, after bearing it about a 
minute. Thickness of metal there '25 + -36 
= - 61 inch. The disc at the top of this pillar 
was intended to give it a firmer bedding than 
it could otherwise have had from its small di- 
ameter. 
4. 
Round hollow pillar of the same form as the 
last, but from a different model. 
External diameter at bottom 2 - 32 inches. 
External diameter near top 1'75 inch. 
Diameter of disc at top of pillar 3 inches, its 
thickness being -9 inch. 
Length of pillar 7 ft. 6J inches. 
Weight of pillar 34 lbs. 9 ozs. 
The pillar, excepting the disc, was cast to be 
everywhere inch thick. Plate XV. No. 9, A 
or B. 
•06 
•09 
•20 1 
direc- 
tion > 
altered 
a little. J 
•28 
•45 
•62 
•80 
6617 
12105 
17593 
20729 
22027 
24043 
25387 
26563 
The fracture took place 2 ft. 1 1J inches from the 
bottom, where the external diameter was 
2'08 inches, and the internal 1*57 inch. The 
thickness of metal on the opposite sides 
there was '35 -|- -15 = -50 inch. The thin 
side was, as often happened, the compressed 
one ; and a small wedge broke out at the place 
of fracture, showing that two-thirds of the 
diameter at least was in a state of tension. 
There was a defect called “cold shot” about 
one-eighth of an inch in diameter in the ten- 
sile part of the fracture, which would reduce 
the strength a little. 
5. 
Uniform pillar, whose section was of the form 
in Plate XV. No. 6, B, where ab = cd = 3 
inches, and the thickness of the ribs = ‘48 inch. 
Length of pillar 7 ft. 6:} inches. 
Weight of pillar 62 lbs. 
The ends were rounded, that the force might 
pass through the axis. 
•04 
•07 
•14 
•25 
•45 
11169 
13129 
15089 
16100 
17175 
17578 
It sunk down, bending in the direction of one 
of the ribs. This experiment was made to 
give some idea of the strength of a connecting 
rod of the usual form, as compared with that 
of a hollow cylinder of the same weight and 
length. 
6. 
Uniform pillars, whose section was cast to be 
equal in area to that in experiment 5, but of 
the form in Plate XV. No. 6, A, in which a b 
= c d = 3 inches, e f = 2f inches. 
Length of pillar 7 ft. 6| inches. 
Weight of pillar 63§lbs. Ends rounded. 
•07 
•13 
•25 
19863 
23895 
25507 
29571 
It broke by bending in the direction a b, c d, 
and was but little bent in the direction e f. 
7. 
Solid uniform cylinder, formed at the ends so 
that the strain would not pass through the axis, 
but in a line half way between the centre and 
the circumference. 
Diameter of pillar 1*95 inch. 
Length of pillar 605 inches. 
Weight of pillar 45 lbs. 14 ozs. Plate XV. 
No. 5, B. 
•96* 
1-30 
11011 
12691 
13195 
*The deflections here given are not those from 
the whole length of the pillar, as in all other 
cases, but from a length of 4 ft. 8§ inches of 
the middle of it. 
3 M 
MDCCCXL, 
