250 
THE COTTAGE GARDENER AND COUNTRY GENTLEMAN, July 17, I860. 
rate of variation once ascertained, a method is thus furnished 
of measuring the heights of mountains. At the city of Mexico, 
7000 feet above the sea, water boils at 200°; at Quito, 0000 feet, 
at 194°; and on Donkia Mountain, in the Himalaya, at the 
height of 18,000 feet, Dr. Hooker found it to boil nt 180°. 
Boiling water is thus not always equally hot, and in elevated 
places, many substances cannot be cooked by boiling. Under 
the receiver of an air-pump, the same elfect is still more 
strikingly seen ; water may be made to boil at the temperature 
of summer, and ether when colder than ice. In complete vacuo, 
liquids, in general, boil at a temperature of 140° lower than in 
the open air. The knowledge of this effect of diminished 
pressure is now largely turned to account in sugar-boiling, in 
distilling vegetable essences, and'in other processes where the 
substances are apt to be injured by a high temperature. By 
increasing the pressure, again, water may be heated to any 
degree without boiling. Papin’s digester is formed on this 
principle. Under a pressure of two atmospheres, llie boiling- 
point rises to 234°; of four atmospheres, it is 294°; of ten 
atmospheres, 359°; of fifty atmospheres, 510°. In a deep vessel, 
the water at the bottom has to sustain the pressure not only of 
the atmosphere, hut also of the water above it. At a depth of 
thirty-four feet, the pressure of the water above is equal to an 
atmosphere, or 15lbs. on the square inch; and thus, at the 
bottom of a vessel of that depth, the water must be heated to 
234° before it is at its boiling-point. This principle has been 
successfully applied to explain the phenomena of the Geysers. 
If a small quantity of water be poured into a silver basin, heated 
above the boiling-point, but below redness, it will begin to boil 
violently, or, perhaps, hurst into steam at once. But if the 
basin is heated to redness, the water will gather itself into a 
globule, and roll about on the hot surface, without becoming 
heated to the boiling-point.—( Chambers's Eneyclopadia.) 
TO CORRESPONDENTS. 
Ashes or Rags (S. I!., Birmingham).—It your orchard soil is clayey, the 
ashes may be applied to your fruit trees with some benefit, but will not 
promote their vigour as the rags unburnt would have done. The burning 
drove away nearly all the carbon and all the nitrogen from the woollen 
rags. They should be applied fresh and not rotted as you purposed. 
Rotting would have removed slowly those valuable constituents which the 
accidental burning removed rapidly. 
Heating a Greenhouse ( W. Wright). —No stove will do unless a tube 
carries off the smoke and fumes from it, and if you have a tube, then gas 
may be employed. We have so heated a vinery. It is quite impossible to 
be more particular without seeing a plan of the greenhouse and the rooms 
adjoining. 
Peaches Mildewing (Ominous).—~We cannot say positively what is the 
cause of your Peaches mildewing, unless we knew the treatment to which 
they have been subjected. In the absence of this information we should 
be inclined to think that you kept your houses too close, and did not give 
sufficient air. 
Pinus insignis Dying (Devonian). —Your Pinus insignis has suffered 
like many others by the severe frost of last autumn. We know of a fine 
specimen twenty-five feet high which has been destroyed to the same 
extent as yours ; and the small plants in several nurseries have been com¬ 
pletely killed. 
SrKRGUi.A riLiFERA—P lantino out Vines in Pots (JacIc-of-all-Tradcs). 
—Neither of your specimens is Spergula pilifera as far as can be seen from 
your specimens. According to the way your greenhouse is worked, the 
Vine, or Vines, will be much safer by being planted on the outside and the 
heads taken inside. By the way,'lose no time in doing so, if you can 
manage to get the heads in without hurting the leaves. See also that the 
ball is laid down perfectly on its side. Being from a No. 4-pot, the roots 
w-ould get too deep at once if the ball were set upright; and there is not 
the least occasion to break such a ball in June, July, or August planting. 
Mulch a yard or more over the ball, which will induce the young roots 
to run near the surface from tho ball, and see that the ball is quite moist 
when planted. 
Culture of the Cactus Tribe (B. H.). —In previous volumes we have 
given much information on this subject; but a scries of papers on this 
branch of floriculture will shortly appear in our columns. 
Plants for Exhibition (Novice). —The six plants you name first are 
all Ferns, and, of course, may be exhibited in that class. Dracmna termi- 
nalis and Begonia Bex may lie exhibited in a class for stove and greenhouse 
plants. Variegated-leaved plants are customarily exhibited in collections 
with flowering plants, if there is no rule directing otherwise. 
Bon Ciiretien Pears Ritening in Succession (Somerset). —The way to 
extend the ripening of Williams' Bon Chretien Pears is, as you suggest, to 
gather them at different periods. Do not allow them to hang on the tree 
till they fall or become yellow; but as soon as you see the colour changing, 
and they part freely from the spurs, let them be gathered and kept in a 
cool and rather dark place. In this way you will not only have a succession 
of them, but also prolong their season. 
Large Strawberry for Early Forcing (A Subscriber).— Notwith¬ 
standing your want of success, there is no large Strawberry equal to Keens’ 
Seedling for early forcing. The Black Prince comes rather earlier, but the 
berries are smaller. The great point in forcing the Strawberry is to have 
the pots well filled with roots early; and when the forcing is commenced, 
to have the roots in action before the foliage is much excited. This is 
secured by bottom heat and keeping the air cool. During growth, a very 
free admission of air, and keeping the plants close to the glass; taking 
care that the whole soil in the pot is uniformly moderately moist, and 
giving a little weak liquid manure occasionally so soon as the berries are 
formed, will secure fine fruit in abundance. Some notes on this subject 
will soon appear in our columns. 
Culture of Griselinia littoralis (An Olcl Subscriber). —The habit of 
Grisclinia littoralis is that of a dense, evergreen, low, hardy shrub, some¬ 
thing after the habit of our Daphne laureola, or Spurge Laurel, but with 
more of the looks of a Bridgesia in the leaves. It is an excellent, new, 
and perfectly hardy low evergreen in the neighbourhood of London, and 
one of the Messrs. Veitchs’ recent introductions. The genus is by Foster, 
and we believe it is not yet sufficiently determined where to place it in the 
consecutive arrangements of botanists. The first account of it as having 
proved hardy near London is in one of Mr. Beaton’s reports of the garden 
at Forest Hill, where the true Spergula was first proved by Mr. Summers, 
of the Crystal Palace Nursery, at page 75 of our twenty-second volume, 
where it is spelt G violin ea, through an error of the press. Griselinia is 
the way Foster left it. Mr. Beaton tells us that he has seen that plant 
again this season, and that the last winter did not brown a leaf of it. Also, 
that he had seen it out in Sir Joseph Paxton’s garden, and that he would 
highly recommend it. The way a peculiar bed was made for it and others on 
trial at Forest Hill, will be found in that report, but we believe it will do in 
any light, sandy soil, such as would suit our hardy and half-luirdy Daphnes ; 
and from what we have seen of it, we should take it to be a plant very 
easy to increase from cuttings or layers in the usual way; also, that it is 
a likely subject to answer under the shade of trees. 
Propagating Cttisus—Grapes Shanking (W. II.). —We presume you 
mean Cytisus for the greenhouse. When your plants are finished flowering 
clean them from old flowers, and give them a good syringing. Ere long 
you will perceive many nice little young shoots from one inch and a half 
to two inches and a half long. Slip these off close to the older shoot with 
a sharp knife. Dress these c’.ean at bottom ty removing two or three 
leaves. Prepare a pot by filling it two-tbirds with drainage. On that 
place some sandy soil, and cover the top with pure sand, and fit the pot 
say four or six inches in diameter with a bell-glass. Water, and let the 
pot stand a day, until the sand is dry on the surface. Then insert the 
cuttings firmly, and settle with a little water again, and place the glass on 
again when the cuttings are dry. Place this pot in a rather shady place 
anywhere under glass. Keep close for a couple of days and nights, and 
then begin to give a little air at night, and shut close down in the morning. 
Attend to what water and shade the cuttings require according to the 
weather; and if you never let them flag for want of water or having too 
much sun, nor yet get waterlogged, you may expect nice tiny plants in a 
month or five weeks. Most of them are also easily increased from seeds. 
Steep the seeds in water at 120° twelve hours before sowing them. The 
White Frontignan is hardly hardy enough for a cool greenhouse. The 
Royal Muscndine.Vtie Golden Hamburgh, or, if you prefer a muscat flavour, 
the Muscat Hamburgh would be better. The long cold wet weather most 
likely is the cause, ii' the Vine is otherwise iu a healthy state. Shanking 
is generally the result of the roots being unhealthy, or deep, or having too 
large a crop. 
Scarino Birds—Roses for a North-east Wall (An Amateur ).— 
There is r.o way of preventing birds from seeds and fruits but by constant 
watching and frightening them away, or by shooting them, or else to cover 
the thing with nets. But you might try an imitation of a volunteer rifle¬ 
man, for if anything on earth will stop the invasion by your enemies that 
is the figure. The best covering of Roses for a north-east, wall in your 
locality is a selection of Sempervirens, which you will find in every 
volume of Thf. Cottage Gardener, and-half a dozen of them would soon 
cover a great length of ordinary walls. 
Hardy Ghent Azaleas (B. Cattcunc) .—There are not more than one- 
half so many kinds of Ghent Azaleas as you ask for. But you might plant 
twenty kinds of them in one bed, and no man or woman between here and 
Ghent could tell, at twenty yards distance, if the bed were not all of one 
kind. Seeing, also, men’s opinions on distinct colours, all we can venturo 
to risk is to recommend you to ask for two plants of each of the six most 
distinct kinds of Ghent Azaleas, and any one of the London or country 
nurserymen whom you see in our advertisements, will send them to you, 
and you may have them as cheap in Belfast or Glasgow as at London, and 
quite as good. 
Various Queries (A Dover of the Garden).— When people send such 
a number of questions at once, they must be content with short answers. 
You have commenced with numbering your inquiries, and we would have 
answered all you require easier if you had continued to do so. We do wish 
some of our gentlemen correspondents would notice the business-like 
mode in which many ladies seek for information. The writing as plain as 
print, and the questions so full and so concise, with not a redundant word, 
and every word so much to the purpose. Now, 
1. We would advise you not to think of a crop next season, but to be 
satisfied with from three to six bunches to a Vine. If your wood is good 
and well ripened, you may fruit them from top to bottom, but do not com¬ 
plain to us if more than half of the berries shank, or the Vines break so 
badly in the succeeding year as to do little good for years afterwards. Half 
a crop at the very most would be enough under your circumstances. The 
only thing you could do to expedite ripening the wood, is to give no water 
to the ground after the end of August, to remove all laterals by the first 
week in September, and give as little air as will just keep the Vines from 
being scorched. If a few inches are given at the top of the house the first 
thing in the morning, that, unless in very hot days, will be enough. 
2. Your Nectarines, &c., will do so long as they are not overshadowed, 
and the Fig and Apricot will do until the Vines are fully established. Then 
the shade will be apt to be too much for thoroughly indurating their 
wood, unless your rafters for Vines are three feet at least from the ends of 
the house. 
3. The Muscat Hamburgh is comparatively a hardy Vine : nevertheless, 
we would prefer having it in a vinery where a little fire heat could be 
given—not because we have any doubt as to its growing in your unheated 
house, but we should doubt its having its peculiarly rich muscat flavour, 
and more especially if the autumn happened to be dull and cloudy. The 
form of the hunch is somewhat like that of the Hamburgh. The individual 
berries are rather longer, more oval, but much the same in size. The 
