THE CORREA. 
383 
heat as well as the front, the bottom, and top ; 
and this is perceptible a few minutes after a fire 
is lighted. A well-built furnace, with a proper 
damper, is capable of being banked up with 
ashes to last all night, when the severity of 
the weather requires it. The cost of this, 
as compared with a boiler and its pipes, is a 
great consideration, but the convenience is 
far greater. A greenhouse should never have 
a fire except to keep out frost or dry the 
place, for damp is a very destructive visitor. 
In this case, the superiority of the brick-flue 
is worth notice ; the heat is generated so rapidly 
that advantage can be taken of a few hours 
fine weather to light the fires and open the 
top windows, or rather sashes ; and it ought 
not to be lost sight of, that iron boilers and pipes 
take as much harm lying idle as they do at 
work. Besides, iron pipes are not sightly, 
while a well-built flue is an excellent support 
for the front stage on Avhich generally the 
most delicate and valuable plants are placed. 
We need hardly point out the advantage of 
generating the heat under the lowest part of 
the roof, and yet we go into some houses 
where the principal part of it is generated at 
the back, so that the heat, which rises perpen- 
dicularly, has to get to the top of the roof in 
the most direct way, and the front only feels 
the advantage when the house is absolutely 
full of the warm vapour ; whereas, if generated 
at the lowest part, it ascends the sloping roof, 
and when at the apex, falls as it cools ; so that 
where the heat is most required there is most 
of it. All that can be said against the flue is, 
that it may require more attention while it is 
in use ; but, as we before observed, this in a 
greenhouse is seldom. 
If hot water is determined on, the conical 
boiler is by far the best, the most economical, 
the most rapidly effective, and requires the 
least attention, let the application be tem- 
porary or permanent, or large or small ; but 
the pipes should be placed under the lowest 
part of the roof, in the same way as the flue, 
and, in lean-to-houses, the heat at the back is 
but of little use. In stoves and houses, to be 
kept at a continuous high temperature, hot 
water saves a good deal of time, because it 
takes some horn's to cool the water ; and if the 
fire happens to be let out for a few hours, the 
temperature does not fall so rapidly, but that 
lighting it again brings it up ; so that things do 
not materially suffer. Still there is no excut^e 
for the extravagant, complicated, and costly 
apparatus that the hot-water doctors recom- 
mend and find simpletons to adopt. If some 
gentlemen were to look to their accounts for 
heating their houses, and could have a peep 
at the cost of others which are better heated 
at one-fourth the cost, they would not be so 
ready to adopt every fanciful theory that was 
brought under their notice. If we had to 
build fifty greenhouses, to be used as such, 
that is, used for the culture of hard-wooded 
and other really greenhouse plants, we would 
have nothing but a simple return flue ; and if 
we could get that along the front, we should 
care for nothing more. One fact ought to 
open the eyes of those who adopt this kind of 
heating. We allude to the astounding fact, 
that the same people scarcely put up tlie same 
kind of heating apparatus twice. Walk into 
any nobleman's or gentleman's place, and you 
will hardly see two of the houses heated alike. 
Hot- water tanks, hot-water open and close 
troughs, hot-water pipes, all shapes and varie- 
ties of boilers ; some heating a large house 
with a five or six gallon conical boiler ; an- 
other, of half the size, with a thirty or forty 
gallon boiler to supply it. The very Horti- 
cultural Society, adopting professedly the best 
plans, wear out a couple of boilers in a short 
time for their large conservatory, and then 
change to a totally different principle, to 
give place in turn, no doubt, to some other 
schemer's theory. In short, there is nothing 
worse managed, at this moment, than the 
heating of horticultural buildings. Let any- 
body wade through the stuff that has been 
written about the Polmaise heating, and the 
subject palls upon the senses. Thousands 
of pounds have been literally fooled away in 
plans under that title, but as widely removed 
from it in principle as a horse from a hen. 
The original Polmaise heating, though not all 
we like, was at least rational and economical ; 
but we have seen twenty houses heated upon 
what is now called the Polmaise plan, where 
there was hardly one feature of the original 
plan left ; still our principal objection to all 
the complicated plans is, that they seem studied 
varieties to increase expense ; and we repeat 
that the most simple and efficacious, the most 
easily managed, and the cheapest for hot- 
houses, are the conical boilers, supplying pipes 
that range along the lowest part of the houses, 
that is to say, the part where the roof is 
lowest, as the front in lean-to-houses, and 
the sides of those with ridged roofs ; and 
brick flues for the greenhouse. 
THE CORREA. 
There is not a more deserving plant iu 
greenhouse culture than the Correa and its 
varieties. The original Correas : alba, pul- 
cliella, and speclosa, are very old acquaint- 
ances, and there is a story told about the 
introduction of the latter that may be worth 
repeating: — A nurseryman was once standing 
at his door, in Islington, when a boy passed 
with a pot in his hand, carefully covered up 
