50 ON HEATING A PIT FRAME. 



b b is a cylindrical boiler, 16 inches high, and 12 inches in 

 diameter, containing within it a similar and concentric cylinder, 

 of the same height, but only eight inches in diameter. The Iwo 

 cylinders are connected at top and bottom, forming a hollow cylin- 

 der, which is my boiler. The small inner cylinder being the fur- 

 nace, a pipe 2i inches in diameter connects this boiler with a cast- 

 iron water pipe, 4 inches in diameter, and 9 feet long, placed hori- 

 zontally along the front of the pit inside, and closed at either 

 extremity by a wooden plug, through one of which passes the pipe 

 which connects it with the boiler, whilst the other is pierced for a 

 small air-pipe. A steam-valve on the top of the boiler, and a fill- 

 ing screw like that attached to the oil-vessel of a lamp, completes 

 the apparatus ; the bottom of the furnace being formed by a cir- 

 cular grate, resting on three brackets about two inches from the 

 bottom of the furnace cylinder. A moveable cover with a chimney 

 to it, capable of being closed by a damper, regulates the fire. The 

 boiler and iron pipe being filled with water, either through the 

 filling screw or by a funnel attached to the air- pipe, a fire is lighted 

 in the furnace ; a small quantity of coke is requisite to light it at 

 first, after which cinders are the only fuel ; and so slow is the 

 combustion, when properly regulated, that this small fire will 

 remain alight eleven hours without any addition of fuel, and keep 

 the water nearly at boiling heat the whole time. My pit is 10 ft. 

 6 in. by 6 ft. 9 in. ; and 1 find the four-inch pipe rather too power- 

 ful a heater, as it raises the temperature upwards of 30 degrees, 

 and requires air to be given all day long : a three-inch pipe would 

 probably be quite sufficient, and judging from the power of my 

 boiler, I reckon that it would produce sufficient heat to keep a 

 twelve-light pit from 12 to 15, perhaps 20, degrees above the 

 external air. My boiler is made of tin, which (the furnace being 

 lined with fire tiles) will last some time; and the whole expense 

 of the apparatus does not exceed £2 5s. Its consumption of fuel 

 is very small. Of course, such an apparatus is susceptible of 

 several improvements, many of which I have in contemplation ; 

 but from its extreme simplicity and utility, I hasten to make it 

 known, even in its present state. As the boiler is not bigger than 

 a wateriug pot, it may be detached, and taken away when not in 

 use. 



A CUXTIVATOR OF CAPS BoLBS. 



