304 



FORCING GARDEN. 



paratus exist at Syon House, the princely seat of the Duke 

 of Northumberland, near Brentford, and in the nursery 

 garden of Messrs. Loddiges at Hackney. At the latter 

 place, glazed houses, to the extent of almost a thousand 

 feet in length, and forming three sides of a square, are 

 heated solely by steam from one boiler. The boiler is of 

 an oblong shape, measuring eleven feet by four, and is 

 formed of malleable iron. In certain narrow houses in- 

 tended by Messrs. Loddiges for green-house plants, a sin- 

 gle steam-pipe is found sufficient. In other houses of con- 

 siderable height and breadth, or where a higher tempera- 

 ture is required, as in the palm-house, the steam-flue is 

 made to describe two or three turns. 



Water, contained in large vessels or pipes, is sometimes 

 heated by steam, and so made the medium of conveying 

 caloric to the atmosphere of glazed houses. The annexed 

 figure represents an example of this arrangement. In the 



Fig. 24. 



%# 



instance here given, a small steam-tube, one inch in 

 diameter, enters a water-pipe eight inches in diameter, 

 and twenty-eight feet long, wholly within the forcing- 

 house ; it passes into the large pipe at the centre, and 

 after traversing its whole length and returning, it issues 

 out immediately below the point at which it entered. It 

 then forms a siphon, by which the condensed water is con- 



