864 
ME. HODGKINSON’S EXPEEEMEXTAE EESEAECHES 
ness of the metal in the outer ring of the hollow castings : on this subject we shall see 
more further on (page 867). 
According to the first supposition, the values of x for a hollow pillar and for a solid 
pillar are nearly as 22 to 20, and on the second supposition, nearly as 23 to 21. Of the 
two irons, the No. 2 seems to be somewhat the stronger, as appears also from the next 
article. 
Relative Strengths of solid Pillars of Low Moor Iron^ No. 3, and those of ^o. 2 of the 
same Iron. 
From the experimental researches* we have for solid cylindrical pillars of Low Moor 
^ 3*55 
iron. No. 3, as a mean from ten experiments on small pillars, w= 98922 Xyiy, where w 
is the breaking weight in lbs., d the diameter in inches, I the length in feet, 3-55 the 
power of the diameter, and 1‘7 the inverse power of the length on which the strength 
depends, nearly, and 98922 lbs. the strength of a pillar 1 foot long and 1 inch diameter. 
To make the comparison above, we shall adduce the results of the pillars in Table II. 
Exp. II, 12, and Table IV. Exp. II of this research, from which we obtain, by the same 
method of computation, for the strength of a pillar I foot long and I inch diameter of 
Low Moor iron. No. 2, — 
lbs. 
From Table II. Exp. II ... . 100684 
From Table II. Exp. 12 ... . 102668 
From Table IV. Exp. II ... . I005I8 
Mean .... I0I290 
Whence the strengths of Low Moor iron. No. 3 and No. 2, are as 98922 to I0I290, or 
as I to I’02394, by which the strengths of the pillars of Low Moor iron. No. 3, must be 
multiplied to obtain those of No. 2. 
Two other small solid pillars in the preceding abstract, compared with the three in 
the present, give 98544 to 101290, or 1 to 1’02786. 
Strength of Pillars dependent on their Lateral Dimensions. 
In long pillars with their ends fiat we havef , in cylinders 60^ inches long, comparmg 
the strength of that of 
•77 inch diameter with that of -997 inch diameter, w= 3-606 
•77 inch diameter with that of 1-29 inch diameter, 3-641 
•77 inch diameter with that of 1'56 inch diameter, w= 3-495 
•997 inch diameter with that of 1‘29 inch diameter, 3-670 
•997 inch diameter with that of 1-56 inch diameter, w= 3-428 
Mean . . . w= 3-568 
* Philosophical Transactions, 1840, Part II. p. 402. 
t Ibid. p. 397. 
