OF THE ATMOSPHERE OF HOT-HOUSES. 307 



of the coming changes of his own peculiar climate, and many 

 of the lower animals are also highly sensitive of changes ap- 

 proaching, especially the feathered tribes. Every person is 

 more or less familiar with these facts. We reason, therefore, 

 from the lesser to the greater; and if, in the absence of compara- 

 tive calculation, or the comparison of the results of one season 

 with another, if, in fact, we consider what are the attainments 

 of instinctive knowledge alone, we are justified in believing 

 that, from established principles, the result of learned inquiry 

 and deep investigation, and the application of science extending 

 over many successive years, many useful facts are already 

 known and clearly explained for our practical guidance. Aided 

 by these researches, man's ingenuity has already turned these 

 elements to a useful account, and made them subserve his pur- 

 pose, powerful though they be. But, in rendering these pow- 

 erful and all-pervading elements subservient to our will, the 

 object of that will must be undeviatingly directed to the imita- 

 tion of nature. To exceed, or even reach, in every case, the 

 perfection of the pattern, is impossible ; but the more closely it 

 is kept in view, and the more nearly it is attained in our artifi- 

 cial performances, the more perfect will that performance be, 

 and the more exactly will our own ends be answered. Any 

 departures from the principles suggested by the examples set 

 before us in nature, through an over-hasty desire to arrive at 

 the object by a nearer road, not only defeats the intended pur- 

 pose, but also makes the ultimate attainment of that object 

 much more troublesome and expensive. The subject of this 

 treatise affords too many examples of this fact; and, though 

 these examples may remain unnoticed by some, and uncared 

 for by others, their baneful influence on the progressing art 

 of horticulture is neither distant nor obscure. The various 

 structures for cultivation are, indeed, much improved of late 

 years ; so, also, are the methods of applying heat, air, vapor, 

 and water. All are so easy, and so much improved, that we 

 sometimes hear practical men observe, that this or that principle 

 or system cannot be beaten or improved ; yet the very best con- 

 structed apparatus, and the most perfect methods of applying 

 heat, vapor, air, and light, are capable of astonishing improve- 



