Features of a Storage House. 439 
ground may be made to answer the purpose. A 
building wholly on the surface, however, is more 
likely to give variable temperatures than one which is 
partially under ground. An ordinary house cellar, if 
it has good ventilation and is not too dry or too 
warm, may answer very well for the storage of fruit; 
but it is ordinarily best, both for purposes of storage 
and for health, that the fruit cellar should be a sepa- 
rate structure if products are to be stored in any 
quantity. The requisites of a good storage cellar for 
fruit are chiefly four: protection from frost; the 
ability to secure a uniform or unvarying temperature 
of 40° or below; facilities for ventilation; and air 
which is moist enough to prevent evaporation. 
The protection from frost is secured either by 
sinking the building below the surface of the soil, or 
by making two to four air spaces in the walls in 
that portion which stands above the earth. The ven- 
tilation should include facilities for removing the warm 
and impure air from somewhere near the top of the 
structure. Some kind of a shaft or chimney construc- 
tion, with a valve or shutter which can be opened or 
closed as necessary, will answer this purpose. In 
buildings which are above ground, it will be often 
necessary to provide some means of taking in the 
cold air near the bottom of the building, especially 
before the cold weather of winter sets in and after 
the warm weather of spring begins. Cold air being 
heavier than warm air, it settles upon the surface of 
the ground in still nights, and if the floor of the 
storage structure is two or three feet below the top 
