on rendle's tank system of heating by hot •water. 237 



capable of being carried out to any extent, and is at once simple and 

 economical. Mr. Rendle has given full particulars of it in a pub- 

 lished pamphlet, -which he forwarded us. In describing it to our 

 readers we can only do so briefly, but enough to show its principle, 

 as acted upon very successfully by a correspondent. 



Mr. Rendle, in June last, forwarded to the London Horticultural 

 Society a paper upon the subject, which was read at one of their 

 meetings. The main point in which it differs from other methods is, 

 that the hot water, instead of circulating round the house in pipes or 

 open gutters, is contained in the centre of the building in a wooden 

 tank, upon the lid of which is a layer of bark or sawdust, raised 

 three or four feet above the floor, for the reception of pots of cuttings, 

 plants, &c. This tank is divided lengthways by a partition in the 

 centre, with the exception of about two inches, which are left open at 

 one end to allow the water to circulate ; its opposite extremity is 

 connected with a small boiler by means of a pipe. The water, upon 

 becoming heated in the boiler, flows through the pipe into the tank, 

 and, after passing round the latter, returns to the boiler by another 

 pipe : in this manner the circulation of the water is kept up. 



The tank in a small house is about nine inches deep. Its lower 

 part is formed of wood, and the upper of slate, one portion of which 

 is covered with tan for plunging in cuttings, &c. ; the remaining 

 part is left bare, so that, on sprinkling it with water, a copious 

 vapour is obtainable. The waste of water in the tank is trifling; 

 when, however, it requires to be replenished, it is easily effected by 

 means of a small orifice left for that purpose in the slate covering. 



The boiler, by which this comparatively large body of water is 

 heated, is of diminutive size, and, perhaps, we cannot give a better 

 idea of it than by supposing one of Rogers's to be divided crossways 

 into two ; the lower portion, hermetically closed,"will then represent 

 the boiler in question. As in Rogers's, the fire is contained in the 

 centre, and is supplied with fuel from the top. It stands upon a 

 grating raised a few inches from the floor, and is surrounded at the 

 distance of two or three inches by an iron case, from one side of 

 which the smoke makes its escape through a small chimney. This 

 outer case or covering is almost double the height of the boiler ; and, 

 the more effectually to prevent the radiation of heat from its sides, an 

 iron cylinder slides down through the opening by which the fire is fed, 



