SECTION III. 



METHODS OF VENTILATION, &C. 



1. If we admit the truth of the foregoing calculations, (and 

 we cannot justly reject them, until they are disproved by calcu- 

 lations more accurate, and observations more extended,) then 

 we must acknowledge, also, that the old methods of ventilating 

 hot-houses, which are still in common practice, are contrary to 

 what we know to be right. Hence the question arises. How 

 are these methods to be improved ? Now, I would remark, that 

 the mere system on which a house may be ventilated is of com- 

 paratively little importance, for no method of ventilation will be 

 good, if the atmosphere be unskilfully managed. Various plans 

 have been employed to modify the influence of draughts, or 

 currents of air, many of which can hardly be termed improve- 

 ments, since the general effect is the same as by the old method 

 of opening the top and bottom sashes, which admits a current 

 to rise up beneath the under surface of the glass, and, as it pro- 

 ceeds towards the aperture made by letting down the upper 

 sashes, it carries the ascending moisture along with it, without 

 in the slightest degree mixing with, or purifying, the volume of 

 atmosphere contained in the lower portions of the house. 



2. It has long been an object among gardeners to obtain a 

 motion in the atmosphere of a hot-house ; and to secure this, 

 even machinery has, in some instances, been employed, and, 

 under certain conditions of the atmosphere, these machines may 

 go on very well. But subject to those vicissitudes of climate, 

 so prevalent in many parts of this continent, the consequent 

 result of their adoption is, a complete derangement of all that 

 equalizing regularity which they were intended to secure. It 

 appears to us a matter of considerable difficulty to lay down a 

 definite rule, or propose a particular system of ventilating a 

 house, since almost every locality has some characteristics pecu- 



