In constructing granaries, the principal objects are, strength or solidity of the edifice, and its exposure to the most drying winds.—• In the county of Kent, previously to removing the corn to such a magazine, it is tossed with a shovel from one end of a large room to the other; by which means the lighter substances fall into the middle, while the ripe grain only is collect-ed at the sides or extremities of the room. The corn is then screened, and conveyed to the granaries, where it is spread to the depth of half a foot on the floor, and turned twice in the week: the operation of screening is repeated once a week. At the expiration of two months, the corn is heaped up to the thickness of a foot, for a.simi-lar period, during which it is turned once, or, if the weather be damp, twice in the week, and is also oc-casionally screened. At the end of five or six months, the heaps are enlarged to the height of 2 feet, and turned once or twice in a month, the operation of screening being likewise from time to time continued.
When grain has thus lain for one year, the quantity is increased to the thickness of 21/2 or 3 feet ; it is turned once in the course of three weeks or a month, and screened accordingly. At the expiration of two or three years, it is moved only once in two months, and screened every quarter: but, in proportion to the length of time it is kept, the turning, etc. should be more frequently repeated, in consequence of which the grain will be much improved. In storing corn, it is requisite to leave an area of a yard in width on every side of each heap, into which the corn should be tossed as often as appears necessary. In the Kentish granaries, two square holes are made at each end of the floor, and a circular one in the middle of the building, through which the corn is shifted from the upper rooms into those below, and again from the lower rooms into the upper ones, in order that it may be the more effectually turned and aired. The. screens or frames employed for sifting the corn, are made with two partitions, for the purpose of separating the pure grain from the dust, which falls into a bag. By these precautions, corn has often been preserved sound, and pure for thirty years; and it is a circumstance worthy of notice that, though by long keeping the grain decreases in bulk, yet it will yield proportion-ably more flour, and the bread will likewise be whiter and more whole-some ; as the superfluous moisture only evaporates during the frequent airing.
M. Du Ham el, and Dr. Hales, have recommended various contrivances for ventilating, or introducing fresh air through corn deposited in granaries, with a view to preserve it sweet and dry, as well as to secure it from weevils or other inserts. This object is to be effected, by constructing granaries withi lattice-work, and haircloth at. the bottom. The ventilators for supplying fresh air may be affixed to the wall, either within or on the outside of the granary, beneath the floor, or in the ceiling ; but, in the former case, it will be necessary to place the handle of the-lever externally, as otherwise the person working the machinery would be exposed to suffocation, when the corn is fumigated with sulphur for the expulsion of weevils. Small movable ventilators • may be constructed on this plan, for ventilating corn in large bins deposited in granaries. Similar contrivances may be applied-to the lowest floors of small magazines so as to be worked by men standing on the ground, either within or without the buildings.
In the 8th vol. of the "Letters and Papers of the Bath aud West of England Society,"&e. Thomas South, Esq. gives a description of a cheap and. efficacious ventilator, for preserving corn on ship-board. This machine consists of a forcing pump, with perforated tubes annexed to it; and by means of which fresh air may be communicated to every part of the cargo. — Mr. Souths air-vessel is, for the sake of cheapness, confined to a diameter of 10 inches; but he observes that, if the latter be enlarged to 14 inches, the effect of the machine will be nearly doubled; and if the length of the trough (by the suction - valve) be extended 10 inches, a power Will be obtained capable of ventilating a cargo of 400 tons in the course of one hour. The price of a ventilator on the smaller plan, is computed by Mr. South, at about five or six gui-heas: one on a larger scale might perhaps amount to twenty guineas; a sum which, in either case, enhances the price of corn only at a rate of less than four-pence per quarter, on the first cargo. These machines, if well punted and properly preserved, will continue useful for many years. - A more minute account of Mr. South's invention is contained in the volume of the "Letters," Sec. before quoted, where its various parts are specified and illustrated by an engraving.
To preserve corn in barns or granaries, Dr. DaRwin observes, it is requisite first to make them dry, and, secondly, to keep them in that state ; because no seeds will vegetate without moisture. In order to dry seeds, the heaps should be frequently turned over in warm dry weather: hence, in this cli-mate, the doors and windows of granaries should open towards the south, for the reception of the warmth of the sun, with air-holes round the building, for sufficient ventilation; and which apertures ought to be sheltered from rain or snow, by boards placed tor that purpose on the outside. - Heaps of corn should be surrounded with planks, in order to prevent them from touching either brick or stone walls ; because, when cold north-east winds are succeeded by moist and warm south-west winds, such walls frequently precipitate the moisture from the atmosphere, and communicate it to those bodies which are in contact with them.— According to Mr. Tull, the safest method of preserving a large quantity of wheat is, to dry it gradually in a malt-ki!n on a hair-cloth, with no other fuel than clean straw, and with a heat scarcely exceeding that produced by the rays of the sun.—. In this temperature, the grain is to remain from 4 to 12 hours, in pro-portion to its previous dampness: The vegetative principle of the corn is not destroyed by this process ; as instances hare occurred of its growing when sown, after it had been thus kept for seven years;
With respect to the best method of securing grain from insects, etc. we refer the reader to the article CORN, pp. 68,69.