By John Rogers, Jun., Esq. 371 



tage falls far short of what is necessary. The air of all buildings 

 artificially heated, is dried by condensation upon the glass, and by 

 the continued escape, through open laps or crevices, of saturated or 

 moist air, whose place is supplied by cold and dry air. To imitate 

 nature, it is therefore necessary to provide a constant supply of 

 moisture, equal to the waste by these two causes; the means 

 adopted to supply moisture to the atmosphere is by sprinkling 

 the floor and the plants, and by troughs upon the heating pipes. 

 Sprinkling the floor, is a very imperfect and inefficient expedient, 

 the greater part of the moisture so bestowed sinks into the earth, 

 and very little indeed finds its way to the atmosphere of the house, 

 for the air in contact with the floor of a house, is generally nearly 

 saturated, having lost its capacity for moisture by losing its heat, 

 and it is only when it has reached the pipes, and been again heated, 

 that it becomes capable of taking up moisture, and in this thirsty 

 state it generally has to seek its moisture among the plants. 



The most effectual mode of producing a moist atmosphere is by 

 considerable surfaces of water above the level of the pipes, which 

 surfaces ought always to exceed by a few degrees the mean 

 temperature of the house. The troughs commonly employed are 

 objectionable, only in as far as they are much too small, and becom- 

 ing quickly empty, afford a very temporary supply. To be really 

 efficient such troughs ought to be at least one foot in width by 5 

 or 6 inches in depth, and they should extend the whole length of 

 the house, affording something like one square foot of water surface 

 for every 15 square feet of glass in the roof. In Orchidaceous 

 houses, and those destined to the cultivation of tropical plants, a 

 still greater surface of water is desirable, and for this purpose slate 

 cisterns, fixed immediately over the heating-pipes, as broad as the 

 front shelves, and from one foot to 15 inches deep, may be advan- 

 tageously employed. Their temperature will always exceed that of 

 the house by a few degrees, and the great surface affords an abundant 

 though gradual supply of moisture — they act also as partial reservoirs 

 of heat, and afford the only efficient means of cultivating the beau- 



