a, back wall ; b, rafters ; c, trellis upon which the 

 vines are trained which are planted inside; d, parapet 

 wall upon which the sashes rest at bottom; e, ground 

 level. (Gard. Chron. 1842, 22.) 



How important is the provision of the greatest pos- 

 sible amount of light to our forced plants is known 

 to every gardener, from the fact that in proportion to 

 the deficiency of light does the plant under glass be- 

 come, in the gardener's phraseology, drawn. That 

 is, its surface of leaves becomes unnaturally extended, 

 in the vain effort to have a sufficient elaboration of the 

 sap effected by means of a large surface exposed to a 

 diminished light, for which a less surface would have 

 been sufficient if the light were more intense. The 

 plant with this enlarged surface of leaves becomes 

 unfruitful, the sap being expended in their produc- 

 tion, which should have been appropriated to the for- 

 mation of fruit. 



Mr. Williams made some experiments intended to 

 c 



