the thickness of the mortar, twenty inches at the bottom, sixteen at the top, and sixteen high. The inside measurements are sixteen inches at the bottom, twelve inches high, and twelve at the top. At (b) is seen a flue made of brick alone, and the brick being four inches by eight, the sizes can be easily determined. When good brick are used, and fine mortar, these flues can be well laid up, smooth and neat, and are very durable. Any good brick-layer can make them. I have seen them made with pressed brick as smooth as the front of the best brick buildings of our cities, and have also seen them made of refuse brick, so rough as to be anything but pleasant to the eye. They are not very well known to the mass of American citizens, but are worthy of their attention, for the steady heat they give off, just suited to the grapery, hot-house and conservatory, but are not well adapted to the propagating house, because of the want of success that usually attends them. When used in the propagating house, they assume the shape seen in fig. 18, where (a) is the flue, supported by earth, plank, or a stone slope, (see fig. 18), and (b) is the stove, built of brick, for wood or coal, and (c) is the chimney, and (d) is the propagating table. The various forms that the flue is capable of assuming in the propagating house we need not describe. The principle has just been given, and it can be curved or not, as suits circumstances. Fig. 19 shows a section of the brick flue table, where (a) is the flue, (b) the table, (d, d, d) are the supports of the table, and (e) the boarding that confines the heated air beneath the table (see fig. 19). A more permanent structure would, of course, be to support the table on brick walls, as at (ƒ), which would confine the heated air and hold the heat better. But the principle is to confine the air under the table, whether by boards, brick or other material, that the bottom of the table may be hotter than the air over the table. Of course, there must be one or more openings, that can be closed at will, to let the heat at times out, for warming the house, as well as to inspect the flue, and repair it when necessary.

If a table is desired on the end of the house, of course it can be made, and on the opposite side of the house also; and the flue can be bent around on the end and return on the other side, only observing that the flue gently rises all the way around the whole house; and that the philosophy of the flue table is that the fire heats the flue, the flue the confined air, and the air the bottom of the table; and thus, through the equalizing material, the buds are forced on the propagating table. A long, and not a very good way. A very cautious man can do well by this plan, but a careless and negligent man is the last to be aware of his faults, and cannot succeed in more than one bud out of every three, thus making a large and inexcusable loss. As usually operated, we doubt if even more than one bud out of six or seven of our native buds is made to grow. We have been unable to say why the hot air is so very adverse to propagating the grape, but we know the fact.

As a modification of this plan, iron stove pipes have been used; but they rust out very rapidly in such a damp place as a propagating house, and they are less successful than the brick flue. Wherever there is a manufactory of pottery or glazed stone ware, there can be made pipes similar to jugs and jars, only rendered porous by the addition of large quantities of coal dust

to the clay before the pipes are turned and burned. The use of the anthracite dust is to make them less liable to crack by the heat, as pores are left in them where the dust is burned out in the kiln. These pipes can be hung beneath the propagating table. They are made in lengths of two feet, and joined as in x, fig. 20. Though we cannot recommend these very highly for the table, we can speak well of them as chimney flues in many green house structures; and the top joints can be decorated.

As a modification of the brick flues is to be named, the once famous, but now exploded Polmaise system. It is well known what a furnace is in the cellar, which heats the air, and the air ascends by tin or other pipes, and by "registers" is admitted into the rooms to be heated. A plan that the more wealthy of towns and cities use, mainly because the dirt of the fire is confined to the cellar, it appears more neat and genteel, and is fashionable. But on the score of economy and health, it is not to be praised. The propagating house, grapery and conservatory, has solved the reason why a popular prejudice has long ago pronounced these fiery demons of the cellar injurious to health; by showing us that when the heat of the radiating surface in them exceeds three hundred degrees of Fahrenheit, there is some change in the air, that causes it to be injurious to plants, and very unfavorable to the propagating house, and they are oftener far in advance of 300°F. than below. The Polmaise system is this furnace, radiating heat into the air, through iron, brick and other material, which hot air is used to heat the grapery, vine pit, conservatory or propagating house, with hot air flues, chambers, woolen clothes wet with a running dripping of water on them, to restore the vitiated air, and numerous other complications too tedious to mention. We give a sectional view of the circular chamber for hot air (see fig. 12, x) of the house that has been represented in part at fig. 12, for the benefit of any one who may wish to try this system in propagation. In fig. 20, (a) is the furnace for coal in its pit, and (b) is an iron dome over it, (see fig. 20) heating the air which rises under the central portion, and through the openings (c, c) of which there are a number. And this heated air passes beneath the central table, which is the propagating table, and thence divides and passes beneath the walk (c,) fig. 12, to the other table, which is for hardening the roots and maturing the plants, and emerges at (f) fig. 12, into the air of the house. So far is the above system. But we further recommend that the flue make the circuit of the outer table (d,) fig. 20, and discharge the smoke and burnt gases by the chimney (c,) fig. 12. Thus he who wishes can have the benefit of hot air as a bottom heat to his full satisfaction, and if carefully managed will succeed quite well and perhaps as well as he can by any means of heating.

2d. The next mode of heating we name is a much more rational one; the heat is more direct, and the success in the propagation of the buds much greater. It is a system of hot water pipes, that is pipes through which a constant current of hot water runs from a water stove. We take it for granted that the reader, occasionally at least, sees the Horticulturist, and has noticed the advertisements of hot water stoves, especially that of Hitchings; Weathered & Cherevoy. As these have acquired, very justly, the reputation of standard water stoves, and explain the principles of all

hot water stoves, we shall speak of them freely, but by no means not approving of others we do not name.

In fig. 21, is seen the patented stove of Weathered & Cherevoy, No. 117 Prince street, New York city. (See fig. 21.) Figure A, is the stove, B, is the internal arrangement as heretofore made, and C, is their late improvement in the internal arrangement of the water spaces. At D, is seen a horizontal section just below the flue, which is the "top of the inside piece looking down upon it." In all the figures the water enters the stove, by the return pipe (b,) and leaves by the exit pipe (c.) This is an excellent stove. And as every propagating house must have a good heater, the prices are reasonable, ranging from the "smallest size $35," to "No. 5, $125."

Figures 22, show two forms of the stove of Hitchings & Co., 248 Canal street, New York city, (see fig. 22,) and the internal arrangement of their "combination cone and flue boiler, patented 1860." The water enters at (b) and flows out at (c). Their prices are "No. 1, grate 11 inches, $27,', to "No. 5, 24 inch grate, $90," for the "conical boiler." And "combina. tion boiler," "No. 2, grate 13 inches diameter, $60," to "No. 5, grate 24 inches diameter, $130."

Either of these firms will, doubtless, give any further information that may be desired very willingly.

Other manufacturers could be named, but if the mode of heating the water in a water stove is not understood by these two plans we have described, the repetition of figures would not explain it any better.

At this point comes in, too, the price of iron pipe connecting with all such stoves, which is very heavy. Four inch pipe is the only practical size, and costs from 80 cts. to $1.25 per foot according to the style, elbows, labor, &c., involved in fitting the house. "A house 125 feet long by 14 feet wide, for an early forcing house, would require about 800 feet of pipe," and by the job, "would cost about $600." He who heats by iron pipes must pay a heavy bill. Hot water tanks, to be more fully spoken of, cost only about one-fourth, and where lumber is cheap, about one-eight as much as iron pipes and work as surely and easily as the pipe.

If not desirable to buy any of these stoves, we have known of small temporary inventions as a square box of copper, coiled tubing, &c., to be quite serviceable.

In examining these stoves it will be seen that the principle of any of these heaters is that cold or cool water comes by one end of the circuit of pipe to the bottom of the water stove, is heated, and hot water flows out through the pipe at the top of the stove, on account of its lessened specific gravity, and hence the necessity of some distance from the bottom of the stove to its top, as well as in the arrangement of the pipes, so as not to disturb this ascent, as the force is very small, yet powerful enough to make the water flow rapidly when rightly arranged. The water coming out of the stove circulates through the pipes, and in heating the propagating table and house, gives out its heat, and thus has its gravity increased, and by it falls to the bottom pipe of the stove. It is clear that the heat so obtained can be readily applied to a grapery, conservatory forcing house, and propagating table, or any like structure.