as applied to Plant Culture under Glass. 629 



under them; then kindled another quantity to join the former, till 

 the furnace was one body of live coals, which, being properly 

 compacted with coals and wet ashes, and the damper regulated, 

 retained a heat in the pipes, i-egular and lasting, till the morning 

 dawned. Now, the only fault that I. find with Cottam and 

 Hallen's boilers is, that the cross bar or bridge curtails the 

 power of extending this furnace and renders it perhaps rather 

 too limited in severe weather : yet, in every respect, Cottam and 

 Hallen's apparatus gives satisfaction, and is neat and work- 

 man-like. 



Kewley's boiler for his siphon apparatus is a large copper 

 caldron, set upon a circle of bricks, with a very contracted surface 

 of bars, yet plenty of room in the furnace under the caldron. 

 This makes the fire draw well, but the fuel has to be passed 

 through a narrow entrance porch with two doors connected by 

 an iron rod, so that when the outer door folds back, forming a 

 semicircle, the inner one stands open after forming a quadrant. 

 This is done the more effectually to prevent any supply of air to 

 the fire, except through the bars below. The following are a 

 few of the appendages of Kewley's apparatus. Two leaden pipes, 

 being the leading and return au'-pipes, connected with a hand- 

 some brass gin-palace pump and brass stopcock, placed in the 

 stock-hole : a leaden siphon and brass stopcock for emptying 

 the boiler, which siphon, every time the boiler is dried and filled, 

 must be filled by a force-pump ; or, as Mr. Kewley showed 

 me, have the air sucked out by the mouth till the siphon gets 

 filled with water : a cast-iron cistern or feeder, with leaden pipe 

 and ball-cock over the boiler ; as the water expands with the 

 heat, or in case of its boiling, this ball-cock is forced up beyond 

 its range, thereby flooding the fire, from an overflow of water 

 from the boiler. But the best part of the invention still remains ; 

 for, lest these intricacies might at any time become uncontrollable, 

 Mr. Kewley has wisely provided bridles for his pipes, which, 

 when screwed on their mouths, prevent the water from circulating, 

 and, by keeping on the fire, the water in the caldron is made to 

 boil and give out vapour to any extent. Hence, to give Mr. 

 Kewley his due, if there were no other way of raising vapour to 

 excess for orchideous plants, his system might and does answer 

 well for that purpose ; but, in his apparatus that I had the mis- 

 fortune to work, the pipes cracked at almost every joint, and ever 

 and anon admitted air, which emptied the pipes of water; and 

 one night, when pumping (for we had to pump the pipes full 

 every night), a piece of lead about the size of half a pea, having 

 been sucked into the pump about the valves, put us all to our 

 wit's end, for the cracks had emptied the pipes and flooded the 

 stock-hole, and the pump would not fill them again; and, though 

 the water boiled in the caldron, the pipes being empty remained 



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