from May 1, 1830, to April 30, 1840. 435 



unnecessary to renew the experiment with an Arnott stove, in com- 

 bination with a boiler of a more perfect construction. 



Finally, a hot water apparatus, executed by Messrs. Baileys of 

 Holborn,has been applied by Mr. Ainger, the Society's Architect, 

 to heating the wing just completed of the new Conservatory. The 

 boilers are placed in a detached building sixty feet from the con- 

 servatory. The water is conveyed by four pipes, each six inches in 

 diameter, which are enclosed in a dry tunnel open at the ends, but 

 having double walls on all sides. The two thicknesses of wall and 

 the included stratum of air effectually prevent any dissipation of 

 the heat, and the tunnel having a gradual ascent towards the house 

 becomes the means of maintaining a ventilation of warm air, suf- 

 ficient probably to meet the whole winter demand. 



This subterraneous part of the apparatus, instead of causing 

 any loss, will, it is confidently expected, produce its full share 

 of effect as regards heat, with the advantage of a warm instead 

 of a cold winter ventilation, while the conservatory is relieved from 

 the incumbrance of a large quantity of piping. 



The four six inch pipes, as soon as they enter the conservatory, 

 branch off into eight of four inches diameter, the gross length of 

 which is nearly 1600 feet, and they contain, together with the 

 larger pipes and the boilers, 1620 gallons. So large a body of 

 water will maintain the temperature of the house for a considerable 

 period in case of any accident or neglect, and the circulation is so 

 rapid that the whole is heated sufficiently for the purpose of the 

 house within forty minutes from the first lighting of the fires. 



In connection with this subject it may be added, that all the ex- 

 perience obtained at the Garden goes to demonstrate the great 

 inferiority of flues to hot water pipes as a mode of heating. 



Under the head of experiments and observations may be also 

 mentioned the Meteorological Journal, continued to be kept with 

 great care by Mr. Thompson, the Under Gardener in the Fruit 



