292 MANAGEMENT O'F THE ATMOSPHERE. 



next to impossible to admit air without injury to the plants, and 

 incurring the evils which have been already detailed. Such a 

 house as this should, by all means, have these sashes made to 

 open, when requisite, but should also be provided with an 

 under-ground method of admitting air, when the weather is 

 unfavorable for opening the top arid side sashes ; and, in this 

 country, this may be said to be the case for at least three 

 months out of the twelve, during which time air can seldom be 

 admitted in anything like a sufficient quantity, without a posi- 

 tive, though perhaps at the time an imperceptible, injury to 

 exotic plants. 



Various other methods have been adopted for imparting to 

 the atmosphere of a hot-house all the freshness of the natural 

 atmosphere, without a reduction of temperature corresponding 

 to the amount of cold air admitted, and also to effect this with- 

 out an increased consumption of fuel. The following simple 

 method has been carried out with pretty favorable results : 



7. Suppose a house already heated by the common flue. 

 We would propose that a square chamber be built over the top 

 of the furnace, and embracing the neck of the flue for two or 

 three feet, if practicable. This chamber should have a drain, 

 not straight, but of a serpentine or zig-zag form, laid through 

 it, one of its ends communicating with the external air, and the 

 other communicating with the interior of the house. Into this 

 latter opening, a pipe, made of tin or zinc, should be fitted, of 

 sufficient size for the admission of a good volume of air. Let 

 this pipe be laid along the lateral surface of the flue nearest the 

 front wall of the house, not in immediate contact with, but sup- 

 ported by bricks, or some other means, at the distance of a few 

 inches from the flue. Let that portion of the tube which passes 

 along the front be perforated with holes, to facilitate the escape 

 of the warm air, with which it will be filled, into the interior of 

 the house. This done, let a number of small tubes, say one 

 for each light, or one for each alternate light, be fixed through 

 the front wall, or otherwise as may be convenient, one end 

 communicating with the external atmosphere, and the other 

 entering the perforated tube. These smaller tubes should be 



