REMARKS ON STEAM AND HOT WATER. 
207 
you will obtain plenty of tubers. For my part I have quite relin¬ 
quished the idea of cultivating it any more. 
Should my communication be considered worthy of notice, I may, 
perhaps, ere long, trouble you again. And remain. 
Yours respectfully, 
Peter Jenkins. 
Devonshire Road , Chiswick , 
May 2nd , 1835. 
REMARKS ON THE DIFFERENT MEANS EMPLOYED FOR HEATING 
HORTICULTURAL BUILDINGS BY STEAM, AND HOT WATER. 
In our last number an extract, with illustrations, was given, of the 
late Mr. Tredgold’s paper on heating buildings by hot water, read at a 
meeting of the Horticultural Society of London. In that paper it is 
truly said, that, notwithstanding the advances already made in the 
management and application of heat to horticultural and other pur¬ 
poses, it is “ difficult even to imagine the extent to which this power can 
be applied This idea and assertion of the lamented Tredgold w r as 
not lost on those of his own line of business when apprised that such 
was his opinion ; and, consequently, rapid strides have been made in 
improving the apparatus in use for conveying heat by the medium of 
water. 
The principle was clearly laid down by Mr. Tredgold; namely, that 
a boiler fitted with pipe of any moderate size and length, one end of 
which should be inserted near the top, and the other turned round and 
inserted near the bottom of the boiler, a current of the water with 
which the apparatus is first filled would be generated from the top 
round to the bottom of the boiler, as soon and as long as fire was kept 
burning under it. The cause is this: all fluids are heavier or lighter 
according to their temperature; heat rarefies water, and this being 
expanded, rises to the top of the boiler and flows along the upper pipe, 
and, in the mean time, the colder and heavier water in the lower pipe 
finding a kind of vacuum in the bottom of the boiler, rushes in to 
maintain an equilibrium. Thus a constant circulation is continued so 
long as any one drop of it is warmer than another. As the hot water 
circulates, it gives out its heat through the sides of the pipe, and always 
in proportion to the heat of the water, or to the extent of the radiating 
surface of the conveying pipe. 
On this principle all the various methods invented by different 
