iSyi.] HEATING AND VENTILATING. 249 



and the other must be opened to keep down tlie temperature, and to 

 prevent absolute scorching. To be able to manage this firing and 

 air-giving is no small garden-accomplishment. It requires a great 

 amount of watchfulness and "gumption" to work the shovel and 

 ventilators ; and so difficult is it at times to secure the conditions 

 required, that we have often wished we could let heat off or on into 

 hothouses the same as water is let into a cistern, by merely turning a 

 tap, or at all events, that means could be devised by which fire-heat 

 could be withdrawn in the presence of sun ; but we suppose this is not 

 possible. 



It is, however, quite within the limits of the possible to avoid the 

 evils arising from a strong fire and a strong sun more than they fre- 

 quently are avoided. Our coldest nights in March, April, May, and 

 June, are generally succeeded by the brightest days ; and under these 

 conditions we usually have the greatest amount of the evil arising from 

 hot pipes, a bright sun, and fully-opened ventilators combined. Now, 

 to fix a night-temperature, and order it to be worked up to through 

 cold and windy nights, so that at sunrise a certain degree of heat 

 must be indicated, irrespective of violently-heated pipes and a rising 

 sun, cannot be regarded in any other light than a mistake. Much 

 sounder practice do we regard it to fix a maximum and a minimum 

 heat, the one for mild and the other for cold nights ; and to avoid 

 high night-temperatures, taking the example so universally afforded us 

 by nature. Management the reverse of this gives more highly heated 

 pipes, just at a time in the morning when such is not only unneces- 

 sary, but most injurious when accompanied with sun, and calling for 

 ventilation to an undesirable extent, simply to keep down the heat 

 within reasonable limits. It is from this state of things that the evils 

 we are anxious to impress upon the minds of the unexperienced arise. 

 Take, for example, a pit of succession Pines in a bright May morning 

 after a cold night, with the pipes thus heated, a bright sun, and a full 

 flow of ventilation, and what are the consequences 1 Every particle 

 of moisture which rapid currents of dry warm air can lick up is rush- 

 ing out at the ventilating openings, and the young plants are being 

 subjected to a rush of dry parched air, which is pumping the very life 

 out of them. This state of things is not easily counteracted if 

 there be no access to the pits — no paths nor vacant surfaces that can 

 be frequently sprinkled with water to diminish the aridity. We 

 need not tell experienced cultivators that the plants are thus exposed 

 to an ordeal which, if it is prolonged, is sure to ruin them. They 

 soon begin to look dejected and parched-like. Their leaves assume 

 the half-circle fold, and look wiry and stunted, the end being that 

 they show fruit prematurely, and are lost. In the case of Cucumbers, 



