4 
is still to be estimated. For this- purpose, take the heig-ht CG and 
subtract from it AB, the height of the side. This will give the 
height of the line CF, which multiplied by the width FB (which 
ecpials GA or half AR) will give the number of square feet in two 
triangles, each the size of CBF or, in other words, it gives the 
number of square feet in the section BCD, inasmuch as the triangle 
CDF is equal to the triangle CBF. The number of square feet in 
BCD is multiplied by the length AH, giving the number of cubic 
feet in the upper portion of the greenhouse ; which, added to the 
number of cubic feet in the lower portion, gives the capacity of the 
greenhouse in cubic feet. 
Many greenhouses have the sides unequal and the slopes of 
the house unequal, as shown in Fig. 2. In such a greenhouse, one 
must measure the height AB by the width of the rectangular 
portion ABIG, which width is AG, G being a point immediately 
underneath the highest portion of the roof. This, multiplied by 
AH, the length, gives the number of cubic feet in this portion. 
The same is done for the rectangular portion DEGF. We then 
have two triangular portions still to compute. Multiplying Cl by 
IB and dividing by 2 gives the number of square feet in the portion 
CIB, which is then multiplied by AH to obtain the capacity in 
cubic feet. The same is done for the triangle DCF ; that is, DF is 
multiplied by CF and half of the result is multiplied by the length 
AH. 
The number of cubic feet in these four sections are then added 
together to give the sum total of cid3ic feet in the greenhouse. 
After having carefully estimated the number of cubic feet, the 
next point to determine is the amount of cyanide to be used. This 
varies according to the plants which are present. Some plants are 
more susceptible to cyanide gas than other plants and where there 
