90 FERNS IN THEIR HOMES AND OURS. 



and glue being omitted, the moulding or strip of 

 hard wood may be nailed directly to the bottom 

 board as shown in the section, PI. 15, Fig. 3. 



The examples so far given are only to show the 

 extremes in expense of fern-case manufacture. 

 The space to be occupied by the fernery, the 

 height of the window at which it is to stand, &c., 

 must, in each instance, be considered. As the 

 window is high or low, the supports of the fernery 

 must be long or short, so as in either case to bring 

 the pan to a level with the window-sill ; for, al- 

 though ferns do not endure the direct rays of 

 the sun, they do not flourish in a dark room. Be- 

 sides, a situation in a living-room, which may 

 seem to us very well illuminated, may not possess 

 the quality of light in which plants thrive the 

 best. A good illustration of this point, regarding 

 the actinic power of light, is at hand. The photo- 

 graph which forms the frontispiece to this book 

 was taken in a greenhouse whose top of glass is 

 exposed to the south, and required an exposure of 

 two and one-fourth minutes in the camera. Imme- 

 diately afterwards, on the same day, a view was 

 taken in a well-lighted room of the dwelling-house 

 adjoining. The exposure here required with the 

 same lens was twenty-six minutes. It is probable 

 that the same quality of light required to produce 

 a good negative is also necessary to produce good 

 plants. 



