288. Aimosjy/ieric Moisture in Hot-houses. 



liable to leak, and, even if it did not thus fail, the flues would be 

 inaccessible when repair is necessary. These difficulties probably 

 deterred persons from forming cisterns in the only position in 

 which they can be useful. Those generally employed are nearly 

 useless except as reservoirs of water, and even for this purpose 

 their low conducting power makes them undesirable, as the water 

 in them is always too cold to use with advantage. 



In slate cisterns such as now suggested, the much neglected 

 tribe of stove aquatics might find a congenial habitat, and adorn 

 our stoves. Their culture has been neglected principally I be- 

 lieve, because they will not flower without abundant bottom heat. 

 They require a temperature of 75° at the least, and will bear 

 much more ; about 85° is most congenial to them : such a tem- 

 perature in ordinary stoves it is difficult to give them, for they 

 require to be close to the light, and the bark-bed, the only means 

 of affording bottom heat, in most cases is too far from the glass. 

 In cisterns, placed on the pipes in front of a pit, I have had 

 them in great beauty ; iVymphae^a caeriilea with three or four 

 flowers at once, each 6 in. in diameter, and continuing for months 

 in succession : so soon, however, as bottom heat was discontinued, 

 the flowers came few and unfrequent, and dwindled down to the 

 ordinary size of those seen in our stoves. 



In conclusion, for all hot-houses, whether fruiting houses or 

 plant stoves, but especially orchideous houses, I recommend 

 zinc cisterns on the pipes, as above described. In plant stoves 

 I should certainly employ some slate cisterns ; but, to produce 

 the copious dews I describe, the zinc cisterns are necessary, and 

 quite supersede the use of steam. To those, however, who may 

 still adhere to the use of steam, I should suggest the adoption 

 of the contrivance above described, to be employed either with 

 a pipe from any existing boiler, or with a portable boiler con- 

 structed on purpose. The conical boiler would be very compact 

 for this service, but it must be made of copper, or it would be 

 most cumbrously heavy. 



The foregoing observations have been thrown out rather with 

 the view of directing attention to the subject, and assisting others 

 to make more accurate experiments and calculations, than with 

 any pretensions to philosophical accuracy. I have endeavoured 

 to show that the hygrometric defects of our artificial climates 

 may be pretty accurately estimated, and easily overcome ; defects 

 will doubtless still remain. The perfection of nature, and the 

 innumerable compensating devices of Providence, are not to be 

 perfectly imitated by human art ; nevertheless, we may make a 

 much nearer approximation to them than we have heretofore 

 done. 



Sevenoaks, April, 1840. 



