wire gauze, and the gas passes up through the pumice stone, and is there lighted. There are two distinct sources of heat, one by the flow-pipe (c), which passes round the house and returns to the boiler at d, and the other by means of the hot-air pipe (g), which is carried along under a shelf against the back wall, and then out of the house at the other end. The only precaution necessary is to prevent an accumulation of air in the boiler or pipes, and every time the gas is lighted, the stopcock at c should be opened to allow of its escape. The heat should at first be very slight, and may be increased as the circulation is established.
A—Copper Gas Boiler.
B—Wrought-iron Jacket or Cover, to prevent the too rapid escape of heated air and the fumes of the sras entering the greenhouse.
C—Ring Gss Burner.
D-Supply-cistern. This can be placed as shown, or in any convenient position.
E—Supply-pipe from Cistern to Boiler.
E— Flow-pipe, for heated water from Boiler.
G— Return Pipe.
H-Hot-air Escape Pipe
GAS-HEATING APPARATUS OF THAMES BANK IRON COMPANY.
(Boiler 10 inches high, 9 inches diameter.)
Probably the best gas-heating apparatus now before the public is that manufactured by the Thames Bank Iron Company. The apparatus consists of a boiler (a), capable of heat-
