216 



THE GARDENER'S ASSISTANT. 



plates loosely, so that this upper floor can be 

 removed when putting in the ice, and that being 

 covered 5 or 6 inches deep with tan or saw-dust 

 — straw will do if the other cannot be had — 

 the inside arrangement is complete. Two doors 

 should be attached to the opening where the ice 

 is put in and taken out— one on the inner side 

 of the lining and the other on the outside, both 

 opening out. Tan, saw-dust, or straw should also 

 be placed on the top of the ice when put in, so as 

 to keep the air from it as much as possible ; and 

 as the ice is removed it will settle down upon, 

 and still preserve it. Care must be taken to have 

 a drain under the floor of the house to pass off 

 the water which melts from the ice, as it would, 

 if standing there, injure its keeping. 



A much simpler method is that of building up 

 a stack of large pieces of ice on a well-drained 

 site under the shade of trees, and thickly thatch- 

 ing it over with wheat-straw. The stack should 

 be made solid by filling in the spaces between 

 the large pieces with finely-pounded ice. When 

 properly stacked in this way, ice can be kept 

 with little waste for a whole summer. 



It may appear paradoxical, but the substances 

 which are considered the warmest are the best 

 for keeping ice from melting. If we fill a bottle 

 with hot water, and wrap it in flannel, it will 

 keep hot nearly twice as long as if the bottle 

 had been freely exposed to the air, for wool, 

 being a slow conductor, prevents the air from 

 readily acquiring heat from the water. Suppose 

 the bottle to be filled with ice, the same kind of 

 woollen covering will prevent the ice from readily 

 obtaining heat from the air, and consequently the 

 former will be nearly twice as long in thawing. 



In filling the house, the ice is generally 

 broken, or somewhat pounded, in order that it 

 may pack closer, but we have seen large masses 

 put in without breaking; all cavities should, 

 however, be filled with the fragments pounded, 

 and the whole rendered compact by throwing 

 water over the layers. In default of ice, the 

 house may be filled with snow, well beaten, and 

 watered, if not in a wet state ; it answers very 

 well, and may be kept a twelvemouth. Some 

 use salt, but its utility is very doubtful, and 

 according to others it is worse than useless. At 

 all events, ice well insulated from earth and 

 water, and shut out from the free access of hot 

 air in summer, will keep very well without salt. 



[J. B.] 



CHAPTER XVIII. 



HEATING. 



By Flues — by Hot Water— Furnaces— Boilers- 

 Pipes — Warming Buildings by Hot Water — 

 Heating by Steam — Heating by Gas. 



Heat has a constant tendency to equalize itself; 

 hence when combustion ceases, the substances 

 which have acquired an elevation of temperature 

 begin to cool, their heat being communicated to 

 other substances near them, and from these to 

 others more and more remote, till at last the 

 original intensity becomes as it were universally 

 diffused. It may be communicated from one 

 solid body to another, or it may be conveyed 

 to a distance by air or water in motion. 



By employing air or water as a vehicle for 

 heat, we can convey it to a considerable distance 

 from the fireplace, in either a perpendicular or 

 horizontal direction, or in that of any upward 

 incline, but not readily downwards, because 

 gases and fluids become lighter when heated, 

 and consequently ascend. 



Of the two principal modes of warming horti- 

 cultural structures by fire-heat, that by which 

 air or other gas in motion is the vehicle or heat- 

 carrier is the older; the other, by which water 

 in motion is the medium of conveyance, is the 

 more approved, and that which is now generally 

 adopted. 



Heating by Flues. — The flue is a channel com- 

 mencing at the furnace, of which it may be said 

 to be a continuation, and terminating in the 

 chimney. It encloses the heated air and gases, 

 conveying them generally along the front and 

 then the back of the house, by which time most 

 of their heat is imparted to the materials of the 

 flue, and from these communi- 

 cated to the air of the house. 



Although heating by hot water 

 has superseded heating by flues, 

 yet these, when well constructed, 

 answered the purpose exceed- 

 ingly well, as shown by the fine 

 productions, both fruit and 

 flowers, that have been obtained in houses thus 

 heated. 



Heating by Hot Water. — If a pipe, open at both 

 ends, is bent in the form of a U (fig. 279), and 

 water is poured in, it will stand at the same 

 height in both legs, as at a b; but if the water 

 is taken out of the leg a, and spirits of wine 

 substituted, the water will fall below b, and the 

 spirits of wine will rise above a, presuming that 



Fig. 279. 



