GLASS, 109 



glass manufactured in Italy, obstructed nearly all the calorific 

 rays. We may, therefore, conclude that the glass chosen is of 

 a similar character to that employed by the Italian philosopher. 

 The tint of color is not very different from that of the old crown 

 glass, and many practical men state, that they find their plants 

 flourish better under this kind of glass, than under the white 

 sheet glass, which is now so commonly employed." 



We understand the glass employed in the Kew Palm-house 

 has fully answered the intended purpose, viz., of obstructing the 

 most injurious portion of the heat rays; and we have learned, 

 also, that it has answered all expectations as to its influence on 

 the health of the plants, although its perfect utility, in this 

 respect, has been doubted by some practical men. We think, 

 however, that an absolute decision on its merits, in this respect, 

 is rather premature, as we should prefer seeing the plants attain 

 a greater size, so as to fill the structure more completely, and 

 their foliage reach nearer to the glass, before pronouncing defi- 

 nitely upon the calorific effects of the latter. 



As to the appearance of this glass, it is altogether a matter 

 of taste, which we consider ourselves having no right to ques- 

 tion ; and, upon the whole, we think it in this respect unob- 

 jectionable. When viewed obliquely, from a distance, it is 

 slightly green, but when viewed from within, and at ri2:ht 

 angles to its surface, it is clear and nearly white. This kind 

 of glass is highly worthy of the attention of glass-makers and 

 horticulturists in this country, and we have no doubt, when its 

 qualities have been fairly tested and made known, it will be 

 extensively employed in horticultural buildings. 



No kind of economy is more sure to defeat its end than 

 using cheap glass in horticultural structures. Many suppose, 

 if a house is merely covered with glass and made transparent, 

 that all is well. We know this to be a common opinion ; yet 

 we are fully prepared to prove its falsity, not by mere assertion, 

 but by indubitable facts, — facts so clear that the most ignorant 

 in these matters will be convinced, from his own observation, 

 and on a scale so extensive, as to justify the conclusions that 

 have been drawn from them. 



We know of nothing -onnerted with the erection of horticul- 



