208 SUGGESTIONS FOR THE MANAGEMENT OF PLANTS AND PLANT-HOUSES. 
can be admitted at any and every part of the house, but in severe weather it is 
necessary to exercise great caution. Of all the plans which have come under our 
observation for winter ventilation, that of admitting cold air by means of drains 
passing from the outside of the back wall under the house to the heating apparatus, 
and escaping upwards among the hot-water pipes, is the best ; and if some wire 
gauze or perforated zinc be placed along every alternate light at the top of the house, 
the ventilation can be regulated with very great nicety, and without any fear of doing 
injury, so long as the heating apparatus is kept warm. The cold-air drains under the 
house should be of considerable size, not less than nine inches square, so that, in the 
case of ripening forced fruits, a large volume of fresh air can be constantly rushing 
in ; and as the quantity of air admitted will be governed by the escape at the top of 
the house, no fear need be entertained of cold currents, so long as the back venti- 
lators are properly regulated. Of houses thus arranged we have never closed the 
cold-air drains at any time during the last three years, and by strangers the atmo- 
sphere has always been admired for its fresh and wholesome feel. In these houses 
the lower pipe of the heating apparatus is laid in a tank, so that the air receives a 
necessary supply of moisture before it passes among the plants ; and when we require 
a very moist atmosphere, it also passes through a coarse, moist, woollen net, which 
makes it all that can be desired for plant cultivation. Of course, this system of 
ventilation enjoins a waste of heat and an increased consumption of fuel ; but that we 
do not care for, so long as we are sure we are benefiting our plants by the additional 
expense. 
Some modification of this plan we should recommend to every one who is 
desirous of excelling as a plant cultivator, and we would particularly impress upon 
amateurs the importance of guarding against currents in their plant-houses, especially 
during the winter season. Taking the precautions previously pointed out, and 
guarding against over- excitement as to temperature, with due attention to watering, 
and allowing each plant plenty of room, and thorough cleanliness both in the plants, 
pots, stages, and houses, success is certain ; but neglect any one of these points, and 
you will most assuredly and deservedly pay the penalty of your indiscretion before 
another summer dawns upon us. Next month we shall have something to say on 
the classification of plants in greenhouses, &c. 
