MATERIALS OF CONSTRUCTION. 101 



ship may be little experienced ; but where the structures are 

 large and extensive, the results become of the deepest impor- 

 tance, in an economical point of view. 



It is not easy to point out a course wherein these difficulties 

 may be avoided, or to discover, at all times, to whom blame is 

 attributable. Tradesmen, who take the work by contract, prob- 

 ably endeavor to do the best they can with the job they have 

 taken in hand, and it is generally their policy to get over it as 

 easily and as quickly as possible. Gardeners who may have 

 the superintendence of the work, probably do the best they can, 

 but from their wanting the necessary knowledge of the details 

 of construction, are unable to exercise that surveillance which is 

 necessary to the proper execution of the work. 



2. Materials of the Frame of the Buildhig, ^-c. — The most 

 suitable material for the frames of horticultural buildings has 

 lately been made the subject of considerable discussion and ex- 

 periment, which has not been without its use in the elucidation 

 of facts hitherto unknown, or, at least, unnoticed in general 

 practice. The case of wood versus iron has been investigated 

 on various grounds, by practical and scientific men, without, 

 however, coming to a unanimous decision on the superiority of 

 either. In this matter, as in some others like itself, some have 

 adopted extreme views of the various merits and defects of the 

 different materials, and have come to their conclusions by refer- 

 ence to some single or specific property. These views and con- 

 clusions, however, have been of considerable utility in bringing 

 the subject before the bar of unbiased inquiry, which, if it has 

 not already done so, is likely to result in the adoption of modi- 

 fied views, and the recognition of specific principles, that, when 

 fully considered and duly weighed against each other, will ulti- 

 mately lead to a more definite result. 



The use of iron in the construction of hot-houses, like every 

 other really valuable improvement, has met with much opposi- 

 tion from the still slumbering spirit of prejudice, which is gener- 

 ally slow to believe in the superiority of anything different from 

 that with which it has been long acquainted, even when this 

 superiority cannot, on reasonable grounds, be denied. This 



