. The book of the garden. Gardening. " In the longitudinal section, fig. 620, circulation of air in the pit upon which you will see how I have attempted to it acts. The bottom of the pit has a fall make use of the ' Polmaise' for the pur- of 6 inches towards the end at which the pose of economising heat, and causing a boiler is placed. From this lowest part Fig. an air-drain is taken, first downwards, then up the back of the boiler, into an air-chamber above it, and is then con- nected with the hollow in the back wall. When the fire is lighted, and the air in contact with the boiler
. The book of the garden. Gardening. " In the longitudinal section, fig. 620, circulation of air in the pit upon which you will see how I have attempted to it acts. The bottom of the pit has a fall make use of the ' Polmaise' for the pur- of 6 inches towards the end at which the pose of economising heat, and causing a boiler is placed. From this lowest part Fig. an air-drain is taken, first downwards, then up the back of the boiler, into an air-chamber above it, and is then con- nected with the hollow in the back wall. When the fire is lighted, and the air in contact with the boiler, &c. becomes heated, in obedience to a natural law by which it is governed, the heated air ascends, and the cold air presses up to take its place, and so, in its turn, becomes heated, and is again thrown into the pit, at the openings in the back wall. " This circulation of air tends to keep up a constant movement in the atmo- sphere of the pit, and, at the same time, conveys the heat, which would otherwise be absorbed by the bricks and mortar which surround the furnace and boiler, into it. It is the common practice, when tanks are used, to place the covers close down on the top of the tanks. In these pits the tanks are of ^-inch cast-iron, 15 inches across at the top, and 9 inches at the bottom, with 3 inches of a bevel. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original McIntosh, Charles, 1794-1864. Edinburgh and London, W. Blackwood
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectgardening, bookyear18
