63 



by the plan already recommended, where the cold air 

 is made to pass through the tank containing the heated 

 water which warms the soil. By a perfectly practi- 

 cable modification of this arrangement, not only may 

 this result be secured, but also the continual circulation 

 of the internal atmosphere may at pleasure be assisted 

 and accelerated, during the time when it might not be 

 necessary to admit fresh air. This would be an addi- 

 tional advantage. The arrangement proposed to effect 

 this, is to conduct the cold external air through a 

 heated chamber containing the tanks these latter 

 being covered, but also admitting of being opened to 

 any extent to supply moisture or steam in the propor- 

 tion required. The cold air, after passing upwards 

 through the chamber, escapes at the front of the house, 

 and ascends to the upper part of the house, from 

 whence it finds its way downwards near the back wall, 

 and there again enters the chamber, through openings 

 provided for the purpose. The circulation of the in- 

 ternal atmosphere would be thus facilitated and accel- 

 erated, even without the admission of any current of 

 external air, for, of course, there is more or less of 

 this kind of movement going on in the atmosphere, 

 wherever and in whatever form a source of artificial 

 heat is present. Another mode of combining internal 

 atmospheric motion, with ventilation, and by which the 

 cold air is warmed before it reaches the plants, has 

 been practised with very marked success, in a vinery 

 at Park-hill, Streatham, Surrey ; and I have described 

 it in the Journal of the Horticultural Society* as 

 follows : '' This plan consists in passing a zinc pipe, 

 thickly perforated with small holes, from end to end of 

 the vinery, and exactly beneath the range of hot water 

 pipes, which heat the structure. In the outer [end] 



* The Journal of the Horticultural Society of London, \ol. I. p. 114. 



