Imp'oved Boiler for Hot-Jiouses. 141 



Art. IV. On an improved Boiler for heating Hot-houses by hot 

 Water, and on some other Modifications of Hot-water Apparatus. 

 By Mr. John Mearns, F.H.S. 



Sir, 

 The object of this communication is to notice an excellent 

 and most simple hot-water boiler, invented by a very ingenious 

 man in Worcester of the name of Oslar, foreman of Mr. 

 Bradley, plumber and brazier there. He has fitted up one 

 of them for Mr. Smith, a nurseryman of this town, for a 

 new grapery erected by him this summer. It pleases him, 

 and all who have seen it ; and I consider it an excellent 

 modification for heating small pits or frames. 



The boiler for small pits should be capable of containing 

 two gallons. Three-inch bore pipes should 

 be suspended to the front of the pit or frame 

 {fg' 17. a), and the feeder may contain about 

 seven gallons of water, and be constructed of lead. 

 The boiler and pipes of Mr. Smith's grapery are 

 large ; the boiler is of copper, and well riveted ; 

 it contains five gallons, and cost him only 4/. 

 Tlie upper pipes are 3^ in. in the bore, and also of copper ; 

 the return pipes are of lead, but formed with union joints^ 

 to covmteract expansion. His feeder contains about thirty 

 gallons, and works excellently. Mr. Smith says that the 

 Staffordshire pipes, though apparently strong, Avill not an- 

 swer the piu'pose, on account of their breaking so frequently ; 

 and moreover a joint in them cannot be easily replaced when 

 they are what they call spigot and faucet joints, without 

 taking all the rest down to it ; and when metal pipes are so 

 cheap, he thinks them greatly preferable. My copper pipes 

 cost me \s. 6d. per foot, and in the long run they will be 

 found the cheapest and best. 



My boiler, which cost \L 35. 9d., is constructed of strong 

 copper, is oval, measures 18 in. by J 2 in., and is in tiie form 

 and size of such a dish-cover as is put over a roast goose. Mr. 

 Smith's boiler is 28 in. by 18 in.; it rests ujion its two ends 

 over the fire, and the flames, mounting over the two sides, 

 enter the flue or chimney at the top. The sketch {fg. 18.) 

 will illustrate the kind of boiler which I mean. 



In one of the pine-stoves here I have used steam-pipes, 

 jointly with the fire-flue, for the last twenty years, and by so 

 doing a great saving of fuel is effected. Unless ranges of 

 houses are to be heated entirely by steam, it occasions a 

 great waste of fuel if the flue and steam-pipes are not both 

 employed; but in such establishments as those of Messrs. 



