“I afterwards erected Pine-stoves for John Hervey, Esq. of Castlesemple, to be heated by steam; and one of the plant-pits had a chamber below, with a close bottom, into which chamber, steam was thrown by means of cast-iron pipes. About the same time, I was applied to by Sir Hew Hamilton Dalrymple, Bart. (through Mr. James Dodds, his gardener), to examine his Pine-stoves at Bargany, and to report whether I thought they could be improved, as he hitherto had not been so successful in Pine-Apples as he expected. One principal cause was, the difficulty of obtaining tan. Upon my report, it was to be determined, whether to give up the Pine-Apple culture altogether, or endeavour to improve the stoves.
“Upon examining, I advised the heating of the atmosphere of the houses with steam; and in place of using tan, the heating of the bottom of the plant-pit with steam also.” This advice was adopted, and eighteen months after the plan was executed, the gardener, Mr. James Dodds, gives the follow-account of his success.
“It is now eighteen months since I first began to heat the Pine-stoves here with steam. I have thus been enabled to give it a fair trial, and I am fully satisfied that it is superior to the old method of heating by fire-flues. I have found the plants to grow more luxuriantly, and perfectly clean of any kind of _insects_. The moist heat arising from steam is well known to be hostile to all kinds of vermin. It is, besides, more economical: our Pine-stoves here are seventy feet long, it formerly took two fires to keep up the heat of the atmospheric air of the house, whereas in the new method of heating by steam, one fire to heat the boiler is sufficient, except in very cold nights, when I have found it necessary to light a very small fire to the flue, to meet the decline of the steam in the morning, and this only to the fruiting-house in the spring months, when the Pines begin to show their fruit. In short, I have found no difficulty in keeping up the heat of the house to sixty degrees, by making up the fire to the boiler at ten o’clock at night, and at six o’clock in the morning.
“With regard to the bottom heat for the Pine-plants, by steam from the same boiler, I find, by allowing the steam to remain in the chamber below the plants about two hours a day, the pit is kept constantly at the temperature of from ninety to ninety-five degrees, which I have found to be as high as the roots of the plants are able to bear. I would, therefore, say ninety degrees to be the standard height, which I have myself adopted, allowing it to fluctuate down. If our succession Pine-pit had been altered to have been heated by steam, as the fruiting one is, which the boiler is perfectly able to do, the saving in tan alone would more than pay the interest of all the money laid out on erecting the whole steam apparatus.