durability, economy of fuel, and the satisfactory results produced in the growth of plants in houses heated in this manner, it must be evident that this method is the cheapest in the end.

It is generally supposed that the heat obtained from steam or hot water pipes necessarily contains moisture. For those who have had any experience in the use of these methods of heating, it is needless to say that such is not the case. To obtain moisture evaporation of water in some manner in the atmosphere must be effected. This is provided for by attaching to the pipes evaporating pans filled with water, by which the moisture can be perfectly regulated and controlled. The capacity of the boiler and the length of the pipes should be in proportion to the size of the house to be heated, bearing in mind that it is better to have a reserve of heating power for extraordinary occasions. In such cases economy in fuel will be secured, as the fires will not be required to be kept constantly burning brightly.

Fault is sometimes found with the apparatus when it lies entirely with the proprietor of the establishment, who in his short-sighted economy, has restricted the builder in the amount of pipe put into the apparatus.

CONSTRUCTION, &c.

The general plan of Horticultural structures may be as perfect as possible, but if the details are not well carried out, and especially if the workmanship be not good, they will prove a source of never-ending vexation and expense. Insecure foundations, ill-fitting doors and ventilators, imperfect glazing, and inferior workmanship of every description, are evils that skillful gardeners have to contend with, and upon whom the consequences of such defects usually fall, when they should be placed upon the shoulders of the constructor.

Methods for building cheap Graperies and Green houses have often been described, and we find many of these imperfect and temporary structures scattered through the country. Such buildings may be cheap as respects their first cost, but their durability is a question which should enter into the calculations of their builders, as well as the consideration of the original outlay. After a year or two we find them with open joints, leaky roofs, and decaying foundations. The inferior and temporary character of materials and workmanship is often a source of serious loss to their owners, and every building of this description demonstrates the mistaken and short-sighted economy of its projector. It is much wiser and truer economy to expend at the outset, a sufficient amount of money and care to make the structure permanent, and to obviate the necessity of constant repairs. Experience has taught us that if they are well and substantially built, these structures will endure for twenty years with very few repairs except an occasional coat of paint. It need not be demonstrated that the profit and gratification to be derived from a well-built house far exceed those accruing from a cheap and imperfect one, with escapes for the heat in winter, and inlets for cold air and driving snow and rain.

The foundations of Horticultural buildings should be of stone or brick, both below and above the ground, if they are to be of a permanent character. The superstructure should be of the best white pine and thoroughly painted. In building curvilinear roofs the rafters and sash bars should be sawed out in pieces to the regular curve. The rafters being put together in sections, breaking joints are thus equally strong throughout their length. The advantages of sawed bars over those bent in the usual manner, are very great. The thrust of the roof is but slight, and the house always remains in shape. With the bent bars the strain is enormous, as may be seen in the settling of such houses at the ridge, and expansion at the sides, besides the liability of breaking the glass by the constantly varying strain of the bars.

Iron has been frequently and strongly recommended in the construction of horticultural buildings. It has been used, with very satisfactory results in England, and doubtless it may there be found to be the best and most economical material for such purposes. It has been tried also in this country, but the experiment has not resulted so favorably. The main difficulty is that, in this climate, the expansion and contraction of the iron rafters and bars are so great that the glass is continually and badly breaking, and it is very difficult to keep the joints tight enough to repel the rain and the cold air. There can be no doubt that in this country, wood is a better material than iron for these purposes.

Thick and double thick glass has heretofore been used almost exclusively for first class houses, but the high price of glass has of late, compelled the use of a thinner article. It is generally believed that thick glass will resist hail storms better than thin, but on this question practical men differ in their opinions. It is contended, on the other hand, that the elasticity of the thin panes resist a blow better than the unyielding thick one, also that the latter is more likely to be broken by the accumulation of water between the laps of the glass.

We have found that the 8 by 10 size of single thick French window glass, second or third quality, is sufficiently good for Horticultural buildings, and we do not use any other, unless especially called for by the proprietor.

Glazing is often badly executed, half an inch lap, and sometimes more, being often allowed to the glass, from the mistaken idea that rain, in a driving storm, will find its way through. A lap of one-eighth of an inch is amply sufficient in any case. The glass should be well "bedded" down to the sash bar, in putty containing a portion of white lead, and well secured with small iron nails or glaziers points. All putty should be removed from the outside when the work is finished, and the sash bars should then be painted with a heavy coat of thick paint which will close up the joints and render them water tight.

Ample ventilation should be provided both at the top and bottom of houses, so that large quantities of air may be supplied when necessary, as in ripening the wood of vines in graperies, and in "hardening off" plants in green houses before removal to the open air.

By reference to the numerous designs given in this work, the manner of arranging the interior details, such as shelving, tables, walks, hot water pipes, and the general features of construction and adaptation, will be understood.

HOT-BEDS.

The most simple form of Horticultural structures, and one known in almost every garden, is the Hot-bed. To persons of experience in their construction and management, we cannot hope to give any important information, but having seen in many instances the operations of these beds imperfectly performed, we offer a few simple suggestions and directions which will be of advantage to the novice.

The location of the bed should be, if possible, a sheltered one, especially on the north side, while towards the east and south it should be open. This shelter or protection is needed chiefly to prevent an undue radiation of heat from the glass, and the entrance of a strong, cold current of air when the sashes are lifted for ventilation. This radiation is not only hurtful to the plants by causing sudden and extreme changes of temperature, but, if allowed to proceed too far, will cause the heat of the bed to "run out." Let the shelter, therefore, be as thorough as possible.

We have found the south side of a barn, or a tight board fence a good location. The barn would be preferable, on account of its proximity to the materials that furnish the source of heat—the