22 GREENHOUSE CONSTRUCTION AND HEATING. 
the best growers now find that the plants do better in 
structures from 15ft. to 20ft. in width, with about a 18ft. 
rafter. Very little ventilation is necessary, and this only 
along the ridge. 
Vineries may be of almost any form or size, but in order 
to produce heavy crops, roomy and lofty structures are 
necessary, with a rather steep pitch of roof. Plenty of roof 
ventilators should be provided, also the means of admitting 
Fig. 11. 
air along the sides or front, to a moderate extent. Early 
vineries, in particular, ought to be constructed with steep 
roofs, in order to catch the sun while it is still low in the 
sky (see Figs. J—span, and 10—lean-to). 
Peach-Houses should be very light and airy structures, 
with steep roofs and plenty of large ventilators both along 
the apex of the roof and at the sides. Peaches and nectarines 
