: 
ON STRENGTH AND PROPERTIES OF CAST IRON. 365 
Devon irons ; they were 1 inch broad, and had their depths 1, 3, 
and 5 inches, the distance between the two supports being as 
usual, 4 feet Ginches. It is evident then, that if the strength 
of each of these beams, when reduced to the exact size, be 
divided by the square of the depth, the quotient should be the 
same in each case. Hence, taking the mean reduced strength 
of the 1-inch bars for the first number in each iron, the reduced 
strength of the 3-inch bars divided by 9 for the second num- 
ber, and the reduced strength of the 5-inch bars divided by 
25 for the third number, we have 
In Carron, No. 2, hot blast . 452 427 402 
Do. cold blast. . 453 417 414 
In Devon Iron, No. 3, hot blast 537 576 617 
Do. cold blast 448 377 405 
472 449 459 
If we compare the numbers in each line, they differ widely ; 
but taking the mean, they approach nearly to equality. We 
eet Sweeties admit that the strength is as the square of the 
epth. 
