218 VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 



in regarding his knowledge of any system well-founded, except 

 upon experiments and observations of his own. 



Gardeners are, of all others, the best qualified to decide upon 

 the merits of any system of heating hot-houses, and to ascertain 

 its effects upon vegetable life. They are, by necessity, familiar 

 with the habits of plants ; and, by an instinctive practical knowl- 

 edge, (if nothing more,) they are less likely to be deceived by 

 the peculiarities produced by heat and cold, dryness and moist- 

 ure, either in deficiency or in excess. The gardener is able to tell 

 whether his plants be in vigorous health, or the reverse ; whether 

 they are suffering from atmospheric impurity, aridity, or stagna- 

 tion ; and, besides, the necessities of culture compel him to 

 study the causes of such changes and conditions. All gardeners 

 are aware that causes the most dissimilar will produce results in 

 every way identical, while the self-same causes, repeated with 

 the greatest care, and under circumstances where it was appar- 

 ently impossible for them to be at variance with the first, will 

 nevertheless produce results totally different ; and the universal 

 axiom, that like causes produce like results, would sometimes 

 appear to be set at naught. 



It has ever been a desideratum, as regards the heating appa- 

 ratus, especially the hot-water kind, that there should be among 

 gardeners a perfect knowledge of their details, and of the man- 

 ner of repairing them. It is true we know when they become 

 warm, and when they cool ; but, as for the rest, once erected and 

 the workmen gone, they are like a watch, or a doctor's prescrip- 

 tion, they may go wrong, and become unworkable, but we 

 cannot put them right, nor scarcely discover what is the matter 

 with them, till we send for the tradesman; and then, after an 

 hour or two pulling and hammering, dusting and besmearing our 

 plants, turning everything in the house topsy-turvy, lo ! we are 

 told that a joint had cracked, a collar had split, or some such 

 mishap had befallen our apparatus. Facts of this kind will be 

 in the experience of every one who has had much to do with 

 heating apparatus. Now what I would urge is, that no part of 

 a heating apparatus should be under ground, or buried in brick- 

 work so far as it is concerned with the interior of the house. 

 Not. an inch of it ought to be covered up with anything. It 



