56 FRUIT CULTURE UNDER GLASS. 



sists of a sheath of " copper placed over or incasing a 

 row of the front pipes. The diameter of the sheath is 

 one inch more than the hot pipe it encloses, conse- 

 quently there is an open space of half an inch all 

 round the pipe inside the sheath. This cavity is fed 

 with fresh air from the exterior of the house, by a 

 pipe 5 inches in diameter, which springs from the 

 lower surface of -the sheath and passes through the 

 front wall of the house to the external air. There is 

 a valve in this feed-pipe to modify the supply of fresh 

 air at pleasure. In the upper surface of the sheath 

 is a double row of holes, so that the moment the cold 

 air comes into the chamber round the pipe and gets 

 hot, expanded, and lighter, it makes its exit through 

 these holes into the general atmosphere of the house." 



VINERY FOR LATE GRAPES. 



Having shown that a lean-to vinery facing due south 

 is the best form for early forcing, under this head I 

 have no hesitation in saying that for the same reasons 

 that I have recommended the lean-to for winter forc- 

 ing, when the sun is only a short time above the hori- 

 zon, the span-roofed vinery running north and south is 

 best for the ripening of grapes, say after the middle of 

 July, excepting Muscat of Alexandria, which, north of 

 York at any rate, should be in lean-to vineries. A span- 

 roofed house in this position gets the benefit of sunshine 

 longer in summer than does the lean-to. The east side 

 gets the morning sun, at noon the whole roof is exposed 

 to it, and on till late in the evening the west side is 

 exposed to the sun, when it would merely be shining 

 on the end of a lean-to. Besides this, a span-roofed 

 house, from 20 to 24 feet wide, encloses a larger vol- 



