4 BULLETIN 518, U. S. DEPARTMENT OF AGRICULTURE. 
METHOD OF COMPUTING THE CUBICAL CONTENTS OF EVEN AND 
THREE-QUARTER SPAN GREENHOUSES. 
It is essential in every instance that the cubical contents of the 
house to be fumigated be determined accurately, and the following 
is a simple method of arriving at these figures: To facilitate matters 
a diagram indicating the necessary dimensions of the house should be 
made. (See figs. 3 and 4.) 
To secure the cubical contents of the even-span house (fig. 4), 
compute the number of square feet in the rectangle a and in the right- 
angle triangles 6 and ¢ and multiply the sum of the three by the 
length of the house. For example, A=5X20=100 square feet; 
B=5xX10+2=25 square feett; and C=5xX10+2=25 square feet. 
A+B+C=150 square feet. 150 square feet 100 feet (length of 
house) =15,000 cubic feet, cubic contents of the house. 
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Fic.. 3.—Diagram showing method of com- Fic. 4.—Diagram showing method of com- 
puting cubical contents of three-quarter- puting cubical contents of even-span 
span greenhouse. (Original.) greenhouse. (Original.) 
To secure the cubical contents of the three-quarter span house 
(fig. 3) multiply the sum of the rectangles a and d and right-angle 
triangles b and c¢ by the length. For example a=6X8=48 square 
feet; d=18X5=90 square feet; Jb=6X4+2=12 square feet; and 
c=18X7+2=63 square feet. a@+d-+b+c=213 square feet. 213 
square feet X 100 feet (length of house) =21,300 cubic feet, cubic 
contents of house. 
Tn estimating the cubic contents of a greenhouse it is not necessary 
to make allowances for the space occupied by the benches, pots, ete. 
TIME FOR FUMIGATION. 
Fumigation should be conducted not earlier than one hour after 
sunset and should not be attempted when the wind is high. It is 
undesirable to fumigate during extremely cold nights, when the 
thermometer is registering near zero, owing to the necessity of ven- 
1To calculate the area of a right-angle triangle, multiply the base by the perpendicular 
and divide the product by two. ; 
