In the case of onions, false shelving or racks are sometimes provided, which are about six or eight feet wide, on which the onions are very carefully spread, eight to fifteen inches deep, there being sufficient space above the onions to admit of inspec tion ; but the usual practice is to replace the shelving by bushel crates, which are universally used for gathering such products. The crated onions are then stored in perfectly insulated build ings constructed as above described.
The capacity of such storage houses varies from a few hundred to fifty thousand bushels. The prac tice in some regions where onions are carried over for seed purposes is to spread the bulbs on slat racks in open buildings where they are allowed to freeze at the beginning of winter and remain frozen throughout the whole storage period. Under these circumstances it is very important that the bulbs be protected from all possible injury ; even the jar ring of the building must be guarded against, other wise the bulbs will rot at the approach of warm weather in the spring. It is evident, from the nature of the case, that this system can be followed only in regions where the winters are rigorous.
In the storage of Irish potatoes and onions, it is desirable that the products be in contact with the• earth if practicable. The moisture of the earth seems to have a beneficial influence on the quality of the product, if it is to remain in storage for a considerable period. Onion bins and crates, when placed directly on the earth, are less liable to jars and disturbances, which cause loss in the stored bulbs, than when made a part of the superstructure.
Storage houses for sweet-potatoes and onions must be provided with flues and ventilating arrange ments to remove the moisture and to keep the tem perature within the limit of safety. In some cases this involves heating facilities as well as ventilating and cooling apparatus.
Celery pits.—The storage houses or pits for celery are very different in construction and usually con sist of a half-cellar arrangement. A well-drained location is chosen, preferably on soil which is of a sandy character. The buildings are so constructed as to give sufficient head room for storing and car ing for the crop. Buildings of this description are usually about twelve or fourteen feet wide, and provided with side walls two or three feet high, which are fairly well insulated to protect the plants next to the outside, either by banking at the out side or by the style of construction above described.
The roof is then made of boards, usually those used for blanching the early crop of celery in the field. In cases where more permanent structures are de sired, the houses may be constructed of concrete and provided with shingle or slate roofs. Sufficient ventilating flues must be provided to govern the temperature inside the pit ; windows are also nec essary to provide light for those who water and care for the crop during the storage period.
Example of a general-purpose root cellar.
In Figs. 788 and 789 are shown a front and side view of a well-constructed and very serviceable root cellar at the Farm and Trades School, Boston, Mass.
The cellar faces south. The walls are of solid masonry two feet thick, and extending two feet below the level of the earth floor. The front and top only are exposed, the earth bank sloping away from the two sides and the rear. The front wall extends be yond the side walls to retain the earth.
The roof is of two inch matched spruce, tarred and covered with three-ply roofing paper. The ceiling is sheathed, leaving dead-air space. The rafters are 2 x S spruce, and the collar-beams the same. Entrance is through an outer and an inner door, each four by seven feet, set in the center of the front wall. There are four automatic ventilators in the roof, also one over the door and one in each door, all regulated from the inside. On the south side of the interior is a brick wall, extending from end to end, six feet from the side wall and three feet high. From the top of this wall to the ceiling is a double-boarded partition, and a door leads from the main cellar into this smaller room. This is for keeping celery banked in sand. The room has two small ventilators in the roof. In the main room are bins and shelves for different vegetables. The cellar is thirty-nine feet six inches long, and twenty-six feet six inches wide. The interior height is seven feet six inches. The cellar is cool and dry, capable of being kept at a uniform temperature, and will accommodate four thousand bushels.