4 BTJLLETIN 513^ U. S. DEPAETMENT 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 nurnber of square feet in the rectangle a and in the right- 

 angle triangles 6 and c and multiply the sum of the three by the 

 length of the house. For example, A=5X20=100 square feet; 

 B=5X10-^2=i25 square feet^; and C=5X10^2=25 square feet. 

 A-f B+C=150 square feet. 150 square feet X 100 feet (length of 

 house) =15,000 cubic feet, cubic contents of 'the house. 



b- -I \. 



•^— < 



I c 



I 



t 



a 



d 



Fig. 3. — Diagram showing method of com- 

 puting cubical contents of three-quarter- 

 span greenhouse. (Original.) 



■lo'. 



9- 



Fig. 4. — Diagram showing method of com- 

 puting cubical contents of even-span 

 greenhoure. (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 h and c by the length. For example «;=6X8=4:8 square 

 feet; <:Z=18X5=90 square feet; Z)=6X4-h2=:12 square feet; and 

 c=18X7-^2=63 square feet. a-\-d-\-'b-\-G=^lZ square feet. 213 

 square feet X 100 feet (length of house) =21,300 cubic feet, cubic 

 contents of house. 



In estimating the cubic contents of a greenhouse it is not necessary 

 to make allowances for the space occupied by the benches, pots, etc. 



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- 



1 To calculate the area of a right-angle triangle, multiply the base by the perpendicular 

 and divide the product by two. 



