ON THE STEENOTH OE PILLAES OF CAST lEON. 
865 
In pillars of the same length with discs at the ends, comparing 
•51 inch diameter with 1‘00 inch diameter, 
*51 inch diameter with 1-28 inch diameter, 
*51 inch diameter with 1-53 inch diameter, 
•775 inch diameter with 1*53 inch diameter, 
*775 inch diameter with 1*28 inch diameter, 
1*00 inch diameter with 1*53 inch diameter. 
^^= 3•922 
w=3-820 
^^= 3•775 
7?,=3-568 
w=3-578 
w=3-412 
Mean . . , 3*679 
In the larger pillars of the present research, each 10 feet long, and cast from models 
varying from 1^ to 2| inches diameter, the iron being that termed “ Second London 
Mixture” (see Table III. Exp. 21 to 24), comparing the strengths of pillars of the 
following diameters, with then* ends turned flat, we have 
1*530 inch diameter with 2*511 inches diameter, w= 3*5016 
1*541 inch diameter with 2*511 inches diameter, %= 3*6154 
1*530 inch diameter with 2*496 inches diameter, ^^=3*3708 
1*541 inch diameter with 2*496 inches diameter, 3*4840 
Mean . . . %= 3*4929 
In the same pillars rendered quite straight, and cut to be 6 feet 3 inches long, the 
ends being turned flat (see Table V. Exp. 5 to 9), we have, by comparing, as before, 
1*530 inch diameter with 2*511 inches diameter, 7^= 3*3068 
1*541 inch diameter with 2*511 inches diameter, w= 3*2603 
1*530 inch diameter with 2*496 inches diameter, 3*1670 
1*541 inch diameter with 2*496 inches diameter, 3*1179 
Mean . . . w= 3*2130 
Mean from all the above comparisons, nineteen in number, =3*513. 
Strength of Pillars dependent on their Length. 
To find the inverse power of the length on which the strength of solid pillars of cast 
iron, cast from the same model, depends, the pillars being of various lengths and having 
their ends turned flat and perpendicular to the axis. From my former experiments* 
we have as below, x being the inverse power, and the lengths of the pillars varying from 
eighty to twenty times the diameter nearly. 
Diameters considered 
equal. 
Lengths of which 
the strengths are 
compared. 
Value of X. 
Mean value 
of X. 
in. in. 
*77 and -77 
•77 and -777 
*77 and -775 
•997 and 1*01 
*997 and 1*022 
ins. ins. 
60-5 and 30*25 
60*5 and 20*l666 
60‘5 and 15*125 
60*5 and 30-25 
60-5 and 20*1666 
1*843 
1*682 
1*550 
1*691 
1*483 
1*650 
* Philosophical Transactions, ISiO, Part II. p. 399. 
