THIRD SERIES OF TABLES. 
97 
Note. — To find the Scantlings of Red Pine Brest-summers and 
Purlins, — see the Diagrams and Examples p. xxiA\ — xli. 
*** The Scantlings of other kinds of timber to have the same Strength 
or Deflection as Red Pine, are found by the Table of Constants, 
No. 3 ; as in the following Example. 
' Example to the Table of Constants. No. 3. 
By Table IV. page 111, Red Pine 8 feet long 7-18 in.X5-08 in., with 
8X500=4000 lbs. pressure in the direction of the depth, and with 
•50X4000=2000 lbs. pressure in the direction of the breadth, deflects 
each way of an inch. Required the Scantlings of Riga Fir to have 
the same strength, and also the same deflection as Red Pine. 
1. To find the Scantling of Riga Fir to have the same Strength as 
Red Pine. 
By Col. I. (p. 96,) for Riga Fir, c= 1-076; 
7-18Xl-076 = 7-725; 5-08Xl-076=5-466. Scantling, 7-73 X5-47. 
The breaking weight of Riga Fir 8 feet long, 7-73 in. X5-47 in., is 
the same as that of Red Pine 8 feet long, 7-18 in. X5-08 in.; viz., 
8 X 500 X 7-325 = 29300 lbs., in the direction of the depth ; or 
8 X -5 X 500 X 10-36 = 20720 tbs., in the direction of the breadth; the 
pressure being uniform in both cases ; or one half of those weights if 
the pressures act in the middle. 
2. To find the Scantling of Riga Fir to have the same Deflection as 
Red Pine. 
By Col II. for Riga Fir, c= 1-125; 
7-18X1-125 = 8-077; 5-08 X 1-125=5-715. Scantling 8-08 X 5-72. 
Riga Fir 8 feet long, 8-08 in. X 5-72 in., with a pressure of 4000 lbs, 
in the direction of the depth, and 2000 fbs. in the direction of the 
breadth, deflects each way of an inch ; the pressures being uniform. 
