THE HEATING AND VENTILATING OF HOTHOUSES. 325 
The lean-to and semi-span type of early vinery 16 ft. wide should have 
•eight rows of pipes, being about 1 ft. of pipe to every 15 cubic ft. to be 
heated. 
An intermediate vinery, if span-roofed, and 24 ft. wide should have 
twelve rows of 4 in. pipes, giving 1 ft. to about 16 or 17 cubic ft. A span- 
house naturally requires a larger proportion of heating surface than a 
lean-to. 
Peach-houses 14 ft. wide with four rows of pipes have a proportion of 
about 1 ft. of heating surface to every 28 cubic ft., which may be taken as 
a fair medium where early forcing is not attempted. 
Melon and general forcing-houses often have a forcing bed on each 
side, with four rows of pipe below each bed. When this arrangement is 
adopted it is desirable to have more than the usual proportion, as those 
pipes in the -chamber below the bed cannot be counted upon but to about 
one-half their heating value. It is usual to put a row of pipe along the 
side above the bed, close to the front ; but, in addition to this, it is desir- 
able to have some pipes in the footway covered with an iron grating. 
These various circulations should be controlled by valves, as there 
Fig. 1G5. —Terminal Saddle Fig. 1()C.— Terminal Saddle 
Boiler. Boiler, another Pattern. 
will be times when no surface heat may be required whilst a good strong 
heat is needed below the forcing beds. 
There should be ventilators in the wall of the forcing bed for the 
admission of air, and other ventilators above, close to the glass, for the 
escape of the heated air. In this way the temperature can be regulated 
as required. 
It is not necessary to go into the question of boilers. There has been 
more controversy about the merits of boilers than any other detail in 
connection with hothouses. There are numerous patent boilers in the 
market, each one put forward by the maker or patentee as being the best. 
I have had very considerable experience of these during the last forty years, 
and my opinion is that a good deal of what is said in their favour may be 
discarded. 
The old saddle boiler still keeps its hold as one of the simplest and, 
under reasonable conditions, one of the most economical ; but I could 
not advise its use (except under special conditions) for quantities over 
750 ft. of 4 -inch pipe. For quantities from 500 to 2,000 ft. the terminal 
saddle boiler is powerful and economical. (Figs. 165, 166.) It takes 
more depth of stoke-hole than the plain saddle. 
K 2 
