XX 
EXAMPLES TO THE FIRST SERIES. 
Example 4 —Required the Scantlings of Red Pine sufficient to carry 
71 tons, or 150 cwts., uniformly loaded ; and deflect with that weight 
^*of an inch. The breaking weight to be not less than 4 X 160 = 
600 cwts. 
W = 7-5 tons. D = i. 
W 7" 5 
— = — = 7-5 X 8 = 60 tons, uniformly loaded. 
D 8 
The scantlings are given by Table XXI. 
Tf the length clear of the supports be 6 feet, the Scantlings are, — 
9-49X5; 8-93X6; 8-49X7; 6-58X15. 
Here the first six scantlings in the table are rejected, because the 
breaking weight of each is less than 600 cwts. 
The breaking weight of 9-49 X5, is 6-231 X 96-42 = 600-79 cwts. A 
joist 9i X5, contains the least quantity of timber, and is the weakest of 
the 1 1 scantlings in the table to be selected from, to fulfil the above 
conditions. 
Example 5.— Required the depth of a lintel to carry a 14-inch brick 
wall 20 feet high over an 8-feet opening ; the lintel to deflect in the 
middle ^ of an inch. 
Suppose the weight of 1 cubic foot of brickwork to be 125 lbs. or 
1-115 cwts., then the weight upon the lintel is, — 
8 X 20 X -if X 1-115 = 208-13 cwts. 
W = 208-13 cwts. D = A. 
— = z= 208-13 X 8 = 1665-04 cwts. uniformly loaded. 
The breadth being 14 inches, the depth by Table XXIII. is 10-18 
inches. 
If the Imtel carry the ends of a floor of joists 16 feet in length, and 
if the greatest weight upon the floor be 1-5 cwts. per superficial foot, 
the additional weight upon the lintel is 8 X 1-5 X8=96 cwts. 
W = 208-13 + 96 = 304-13 cwts. D = as before. 
— _ ^^11^ _ 304-13 X 8 = 2433-04 cwts. uniformly loaded. 
The breadth being 14 inches, the depth by Table XXV. lis 1 1-38 
inches. 
