THE COTTAGE GAKDENER. 
DlLCEMBEK 30. 
240 
a kind of lierbaceous pcrcninal, dying down to the soil 
edge overy ordinary winter. 
J’liYLLocLADUs TRiciioMANoiiiEs (Maidon-hair-like P.). 
—This is another remarkable New Zealand tree, bearing 
some resemblance to the cnrioiis-leavcd Stilisbiiria adian- 
tifolia, only the leaves arc more divided at the margin. 
When young, tho foliage is a blue-green; but as the 
leaves become old tltoy become of a dark brownish-purple, 
giving the tree a most singular outlandish cappearanco. 
As a contrast in colour, as well as a groat curiosity, tho 
plant is wortliy of a place in a large conservatory. Like 
most of the Now Zealand trees, its hardihood, except in 
highly-favoured situations, is moi-o tlian doubtful, and it 
: is, therefore, safer to give it a gentle protection. A very 
j interesting collection might be formed of trees and 
! shrubs like this that would live in a glass-house with- 
j out heat, but arc not hardy enough to be entirely ex¬ 
posed. The only expense would bo tho cost of the 
building at first, the keeping them clear of weeds and 
insects, and a little attention to pruning, and thereby 
kcojiing them in form. Some day or another I will 
draw up a list of plants suitable for such a cold habita¬ 
tion. 1 am quite sure such a building would bo useful, 
for more plants are spoiled by too much heat than many 
2 icrsons arc aware of. 
P. uuonuoiDALis (Rhomboid or Celery-topped P.}.— 
This is the P. asjdenifolia of Hr. Hooker the younger, 
ft is a native of Van Diemen’s Land. Like its co- 
species, it has a most singular appearance, and is a 
beautiful branching tree, found growing close to the 
sea-shore. It can only bo called a half-hardy tree, 
reixuiring the protection of a conservatory, or a glass¬ 
house without artificial heat. T. Ai’cleby. 
(I'o he coutinved.) 
HOT-WATER versus POLMAISE. 
Some years ago, a warm controversy was carried on in 
our then existing gardening periodicals of the relative 
merits of the two modes of heating noted above. The 
advocates of the newly-invented system of heating by 
propelling currents of warmed air to circulate through 
the interior of the building, insisted that the sluggish 
warmth imparted by hot-water-pipos or tanks, tainted, 
rather than improved, the condition of the atmospheric 
air it acted upon; and though it supplied the necessary 
amount of heat, it was said to be more of a mechanical 
than of a natural kind. Against this imputation, tho 
friends of iron and water pointed to the many instances 
in which the atmosphere of structures intended to bo 
Polmaisc was little more than a compound of smoke 
and steam, supplied separately or together, as tho case 
might be ; while, in some other cases, where those agents 
were kept under proper control, the heat supplied was, 
by certain wayward propensities of its own, all confined 
to ono end, or other jdaco of entrance; coujded with 
those evils was the extravagant use of fuel required to 
furnish heat from so limited a S 2 )ace as that from which 
it was, in the true Polmaise system, confined; this latter 
evil led to tho ajqiaratus taking the character of a 
“ flue ” (either long or short) entering or traversing the 
house; where such was done, the I’olmaiso resolved 
itself into nothing more thair the old-fashioned “ smoke- 
fine,” about whoso action our grandfathers knew about 
as much as wo do. Various improvements, in tho way 
of amalgamating the Hue and Polmaise together, were 
tried with more or loss success, and the latter plan 
itself became so altered in character, that its original 
inventor can hardly recognise it now as having any 
analogy with tho “ hole-in-the-wall,” and “ wet-blaukct-” 
mode by which ho first introduced it. However, it must 
bo admitted, that some of those hybrid contrivances, 
I whereby the merits of tho i’olmaisc and tho smoke- 
llue become united, act tolerably well; and, in some few 
instances, whore good gardening skill is brought to bear 
in tho matter, the production of such Polmaise-hcatod 
structures cannot bo excelled by that of any other con¬ 
trivance whatever ; it is, therefore, only just to infer from 
such results, that tho principle is a good one, but tho 
practical details of working it out rather dillicult. This, I 
believe, its most sanguine friends admit; since none, that 
1 am aware of, have continued long in working order 
without something going wrong, or, it might be, an im¬ 
provement aj'pear feasible. 
I believe tho most successful cases of Polmaisc- 
heating are to bo found amongst the class called 
amateurs ; nurserymen, and others in trade, having 
less interest in novelty than proved utility; while 
a gentleman’s gardener, rccommoncUng tho construc¬ 
tion of anything diil’ering much from what preceded 
it, is supposed to place himself in the position of war¬ 
ranting its utility, and naturally enough strives to make 
it fulfil its intended purposes. So that, in cases where 
the adoption was at his request, J. believe the 2 )lau had 
as fair a trial as could be given to anything where the 
reputation of the adviser was at stake; still, there were 
many cases where it was abandoned, and hot-watcr, or 
something else substituted, and this at a time when 
gardening jroriodicals wore p)ourtraying its merits, or 
decrying its inutility; in fact, tho time chosen was ono 
in which it might bo fully said to have every advantage 
of a fair trial, its advocates and accusers being both 
men of experience, and well qualified, by long piracticc, 
to judge of the merits of anything likely to be of ad¬ 
vantage to the horticultural world ; but the test still lay 
with that mighty disi)euser of justice, “the British 
public,” who, however prone to run away after every 
novel piece of qmackcry, be that a railway or a universal 
medicine, is, nevertheless, sooner or later brought to 
exercise a sound judgment on each individual case ; and 
in the ono regarding Polmaisc, it can hardly be ques¬ 
tioned by its best friends, but that tho public verdict 
has been an adverse one; there may bo those who 
doubt the justice of that verdict, tho same as others may 
differ from that of the Lord Chancellor in other matters, 
but that docs not much affect the case ; for until some 
strenuous friend of Bolmaiso show “just cause why its 
merits have been undervalued, and its defects over¬ 
strained, or rather, until ho be able to improve the ono, 
and diminish the other, Polmaise must certainly stand 
second to hot-watcr as a heating medium.” In this 
view, I believe, 1 am sustained by the groat body of tho 
horticultural world, and certainly by none moi'e so than 
those who, having given it a fair trial, have abandoned 
it as defective. Still, it must be admitted, that there arc 
some instances where it has been found to answer, and 
admirably to ; and where it docs act well, tho condition 
of the )iroducts inside tell, in umnistakeable language, 
how well the jdan suits them. 
Tho advantages of a circulation of air, which it is said 
the Polmaise has over that of other plans, is certainly 
an important adjunct to tho W'cll being of cither the 
animal or vegetable world; but we may yet live to see a 
greater circulation of air in hot-water-heated structures 
than has yet been done by a more liberal influx and 
cHhix from and to tho open air. It may bo true, that 
some expense w'ill attend heating a certain quantity of 
air allowed to escape, but if it be attended with increased 
luxuriance to tho plants grown there, the matter be¬ 
comes one deserving attention ; but this is foreign to 
tho subject of weighing the merits of tho two systems 
as they now stand, so that we must look to tho results 
accomplished in each case; and, giving due attention 
to tho trouble and exjicuso in each instance, wo are 
certainly led to believe that hot - water is, in nine cases 
out of ten, preferable to Polmaisc, as, even with those 
who have managed the latter in the best manner, the 
