20 REPORT ON THE 



Plums, Melons, Raspberries, and Strawberries. All these had 

 a very promising appearance. The forcing houses are mostly 

 wooden structures, about 11 feet high, and 8 feet wide ; they 

 are heated by hot water in copper pipes. The pits for Melons, 

 Cucumbers, French Beans, &c., are heated by hot water, aided 

 by dung linings. The boilers as well as the pipes for this pur- 

 pose are made of copper. This substance appears to be gene- 

 rally preferred to iron for the hot water mode of heating about 

 Paris, even by market gardeners. On the score of economy, 

 they say, that although it is somewhat dearer than iron in the 

 first instance, yet it is ultimately cheaper, inasmuch as it wastes 

 but little, and it is always saleable. As regards adaptation, 

 they can obtain heat much quicker from it than from iron. 

 This property is more especially an advantage in such a climate 

 as that of Paris, where the general clearness of the air admits 

 of a large amount of sun-heat being suddenly accumulated ; and 

 consequently, the quicker the heating apparatus parts with its 

 heat the better. On the other hand, in proportion nearly as the 

 clearness of the air favours a sudden rise of temperature by 

 sun-heat, so does it facilitate the rapid escape of heat by radiation, 

 as soon as the sun's influence is withdrawn ; and hence a 

 promptly heating apparatus is again the most eligible. 



Parallel to a range of forcing-houses, on the opposite side of 

 the walk in front, there are two rows of vines about 4 or 5 feet 

 apart ; outside of these, over half the length of the rows, a move- 

 able frame is placed, with sashes inclined so as to rest below the 

 edges of a board at the top, and high enough to admit of a person 

 walking along between the rows of vines, trained upwards on 

 both sides. When the vines have been grown one year under 

 this structure, it is removed and placed over the other half of 

 the plantation. By this arrangement the vines are grown, one 

 year under glass, and the next in the open air, and so on alter- 

 nately. Finer grapes are thus obtained than by constantly 

 keeping the vines under glass. This fact deserves further con- 

 sideration. 



Supposing a vine is planted in a rich border, and that it is 

 introduced into a house where it is successively forced with 

 abundance of heat and moisture, but with some deficiency of 

 light and air; the foliage may be ample and the shoots gross, 

 but it does not follow that this luxuriant growth is a substantial 

 one, although, under the circumstances, the best system has been 

 pursued. The growth may have progressed steadily under a 

 gradual increase of temperature, like that of the natural climate 

 of the vine. So far as heat and moisture are concerned, the vine 

 under glass need be no sufferer ; but, as regards light, it must 

 suffer to a greater or less extent. That this is unquestionably 



