The economy and simplicity of plan have also been proved by Mr. Harrison having, previously to heating the second house, had an estimate made by an eminent London firm, of the cost of the apparatus for heating the house, the dimensions of which were given. Estimate, 58l. Mr. Harrison objected to the estimate, and desired to have another, with the plan of heating on which the estimate was founded: this was 52l. Mr. Harrison, disapproving both of plan and estimate, made, with Mr. Pratt, a plan, the iron for which was supplied by the same firm, and amounted to 26l., instead of 52l.; and this plan, at half the cost of the other, has most completely answered in every respect. No estimate or plan from London has since been required. It may be added, that Mr. Pratt is now satisfied from experience, that economy in fuel and in labour in attending fires, and the avoidance of night-watching, as well as economy in the first cost, are attained by simple instead of by complicated plans. Any required heat, however high, may be given, and distributed and regulated by the stop-cocks in the different houses, and retained during the severest weather without any care during the night. Mr. Pratt has ascertained that 420 gallons, the largest quantity of water used in the new houses, can be boiled in an hour; and, when it is considered that during the greater part of the year, and the whole of that part in which sudden severe cold can occur, the water in the boiler must always be kept at a certain temperature for the use of the pine and orchideous houses, and generally also let into the botanic house, no difficulty can occur in the other houses. He has found that the upper pipes in the geranium and heath houses become hot in five minutes after the cocks are turned to let in the hot water from the adjoining houses. It must be added, that great care should be taken in the construction of the fireplace and flue; as a most important difference will be found between a wide and ill-constructed fireplace and flue, both in the intensity of heat by any given quantity of fluid, and in the burning of inferior fuel mixed with good; in the keeping in of the fire, and preventing any accumulation of soot, &c. The fireplaces and flues have all been constructed under Mr. Pratt's own immediate superintendence. "The result is, a decided superiority in economy, in first cost, in the use, and in security without-night watching, of simple over complicated plans: and this detail has been given, which might be extended to more minute points if required, in the hope that it may prove useful to amateur gardeners who require hot-houses, and to those who supply apparatus for heating. Many persons deny themselves a luxury they wish to enjoy, from the expense and occasional failures of many of the complicated plans now in use; and more numerous orders, which would be given if the above objections were remedied, would amply compensate those who supply such apparatus. - W. H."
