CONSTRUCTION OF PLANT-HOUSES. 
11 
gulated by the form and size of the entire work; we may, how¬ 
ever, remark, that it is not good economy to allow it to take up 
the best part of the erection, or those places which are covered 
with the glass roof, as an equally suitable position may be made 
for it among the hollow rocks which bound the wall-side of the 
house. Perhaps the most interesting form for its entrance would 
be that of a cascade : be that as it may, its exit should be ob¬ 
scured among loose stones, overgrown with moss and ferns. The 
management of the plants will require that hot-water pipes be 
passed through the main body of the fluid brought into the house, 
in order to prevent its lessening the general temperature. These 
are easily concealed among aquatics, and in winter all the water 
may be withdrawn, if it is thought necessary, when the fixed 
pipes will do good service by warming the atmosphere around 
them. 
The approaches to all erections of this nature should partake 
of the character of the interior. Thus, in the two cases men¬ 
tioned, the first should be entered from a deep cutting or rocky 
cavern, and the latter from a path winding among open banks of 
American plants, elevated sufficiently to completely shut out 
every sign of the structure to which the walk leads. 
In the foregoing brief hints we have mentioned only those 
matters which should occupy attention previous to the commence¬ 
ment of a work of the kind ; and here we would particularly cau¬ 
tion all operators to avoid exaggerating the finish—the great 
danger is, that things of this nature may be over-done. Much 
more might be added on the necessary details, but we leave the 
subject for the present, to proceed with the consideration of what 
seems to require some decided alteration in the common plant 
structure and forcing-house. This will involve, first, the neces¬ 
sity and consequent utility of the heavy rafter, plates, and other 
timbers in ordinary use; secondly, the question of ventilation ; 
and, thirdly, the saving to be effected if it is possible to adopt a 
means of ventilating without the wear and tear consequent on 
the present method. 
That timbers considerably less than those generally employed 
would support the same roof, if the entire of the sashes were 
fixed, we think no builder will deny: it is the friction and strain 
which occurs each time they are moved that renders the extra 
substance necessary. If, then, the proper supply of air (and we 
