PORSYTH’S TREATISE ON THE CULTURE OF FRUIT TREES, &c. 
three feet lower’ than the cieling of the 
ground-floor chamber: the top of the 
pipe is open to the external air, but may 
be closed at pleasure by a stopper; the 
Dbottom of it is also open, and two lateral 
apertures are made, furnished with valves, 
one of which communicates with the up- 
per chamber close to the roof, and the 
other with the lower chamber close to 
the cieling. * The building being thus 
constructed, and the top of the pipe 
closed with its stopper, the lower side 
valve being also closed, the bottom of 
the pipe and the upper side valve being 
open, as soon as the rays of the sun enter 
the building, the particles of heated air 
will rise through the rest and accumu- 
late in two strata, one beneath the roof 
and the other beneath the cieling ; a 
quantity of cold air, in proportion to 
the enlarged bulk of that which is heated, 
being forced through the side hole, near 
the bottom of the upper chamber. In 
the course of an hour or two the stratum 
of air in the upper part of the lower 
chamber will have increased in thickness 
till it becomes parallel with the open ex- 
tremity of the pipe of communication ; 
all the surplus therefore of heated air 
will rise up the pipe, and be discharged 
under ae roof of the upper chamber, by 
means of the side valve. This process 
will be going on as long as the sun shines 
on the house, so that towards evening 
the upper chamber or reservoir will be 
Arr. VIII. 4 Treatise on. the. Culture 
709 
filled with hot air. Upon the removal 
of the sun’s light the air of the house will 
begin to cool, though very slowly ; its 
dimensions will in consequence contract 5 
and to supply the vacuum that would 
thus be formed, a current of cold exter- 
nal air begins to set in through the side 
hole, near-the bottom of the upper cham- 
ber; but as the pipe is the only commu- 
nication between the two chambers, and 
as it Opens into the upper one just under 
the roof, it is obvious that no cold air 
can get into the lower chamber till the 
whole of the heated air in the upper one 
has first passed in ; and before this takes 
place, except in very severe and cloudy 
weather, the rays of the sun will again 
find their way into the house, and fur- 
nish a fresh quantity of heated air. In 
severe weather, Dr. Anderson preserves 
the heat of the house ata proper degree, 
by means of a single Argand lamp. 
We have no doubt that houses on this 
construction will be found more regular 
in their heat, and much more economical 
tham those on the usual plan, though we 
are by no means disposed to attribute to 
them so vast a superiority as Dr. Ander- 
son does ;.who, though he is himself 
possessed of a hot-house built according 
to his own plan, declines giving us the 
result of any experiments made in it, on 
account of “ various unavoidable mis< 
takes in a first construction,” efit 
fa! 
ana Management of Fruit Trees, Sc.. By. 
“Wirriam Forsytu, F. R.S. oo F.8: A. Gardener to his Majesty at Kensington 
and St. James’s. 8vo. 
»__ IN our former volume, p. 767, we 
have given a particular account of this 
valuable work, and have noticed the 
‘controversy between Mr. Forsyth and 
Mr. Knight, relative to the efficacy of 
the new mode of treatment introduced 
by Mr. Forsyth, in renovating the vigour 
of decayed and worn-out treés. 
‘shall, therefore, content ourselves with 
extracting, without further comment, 
‘the postscript to the present edition. 
‘© Since the printing of this third edition 
was completed, I have been fortunate enough 
to have derived an accession of most respec- 
table testimonials, tending to remove any 
‘doubts that may have arisen in the public 
mind respecting the verity of my statements 
on the subject: of my composition. 
i a The visit which IT had the honour to: 
Teceive from the undersigned gentlemen was 
wholly unexpected on my part; originating, 
—_ 
* 
Third Edition. 
We: 
'as I am given to understand, solely from a” 
eonversation among themselves, and a desixe ¢ London, Nov. 17, 1803. 
on the part of some of the company to re- 
move the doubts of the others. 
‘To Mr. Forsyth, Royal Gardens, Kensington. | 
* SIR, 
« As you had the goodness lately to give. 
us an opportunity of exaniining several trees; 
in Kensington Gardens, in the various stages 
of renovation, or filliag-up with new wood ; 
and as reports have been circulated, tending 
to diseredit the efficacy of your process ;—we 
feel it an act of justice, not only to you, but 
to the country, which is deeply interested in 
your discoveries, thus publicly to declare, that 
the statements you have published on the. 
subject contain nothiyg more than the truth. 
J.C. Letsom, M.D. E.R.S, &e. 
Wiruram Woopvitiz, M.D. | 
James Sims, M. D. 
Wirziiam Norris. By) 
JoserpH Hart Myers, M.D. 
AstLey COOPER. ~ 
Epwarp CoLEMAN. 
H. N. Wixuss, F. R.S. &e2 
Laz 3s 
io, 
