hnpro'oements in heating by Hot Water. 21 



in the first experiment. {Jig. ^.) When the apparatus was 

 charged with water, and heat apphed, I found the cold water 

 in the tray gradually become warm on the surfaces and as 

 the large pipe became hotter, the water in the tray increased 

 in heat, until the bottom became too hot to keep the hand 

 there. Being desirous of knowing how long a time the par- 

 ticles of water occupied in coming from the bottom of the 

 boiler to the tray, and the rapidity with which it moved in the 

 apparatus, I threw into the boiler half an ounce of archil, 

 which, from its gravity, descended to the bottom of the boiler, 

 and in half a. minute it had risen and passed through a space 

 of 5 or 6 ft., and entered the tray. I3y colouring the water, 

 I had an opportunity of remarking the action of the water as 

 it proceeded from the boiler to the tray. It entered at the 

 upper pipe, went direct to the opposite side, and, instead of 

 descending through the i"eturning pipe, the colour turned to 

 the right and left, and came back again ; and so continued 

 moving backwards and forwards, until the all uncoloured water 

 was expelled, when it began to follow the course of the pure 

 water; affording a beautiful example of the difference in 

 density between hot and cold water. In these experiments 

 the water was heated to about 130'^ ', and the difference in the 

 boiler and tray, where the hot water entered, was 1°; but, at 

 the end of the tray (in consequence of evaporation), it was 

 about 6^. The heat can be cut off from the tray by corking 

 slightly the lateral delivering pipe, as well as the returning 

 pipe; or by stop-cocks, as in the sketch : so that by this means 

 you can not only steam your house or frame, but increase its 

 heat several degrees at will. I proved this by closing both 

 lights of my frame, and opening the pipes of the tray : in ten 

 minutes the heat had increased 10^ throughout the bed. By 

 introducing into the main delivering pipe a circular valve 

 (working through a small tube as high as the top of the boiler, 

 with a handle on the outside, to open or shut it), you would 

 be enabled to turn the hot water on, or prevent it increasing 

 the heat of the house or frame. Even were the water to boil 

 in the boiler, by this valve it would be prevented from over- 

 heating the pipes ; indeed, I should think you might regulate 

 it to the exact heat required. (A stopcock would answet 

 best, but they are expensive when large.) 



As I think this may prove a most important application of 

 hot water, I will not apologise for being minute. Having de- 

 tailed these simple experiments, I will now attempt to describe 

 the method I adopted in applying them. I did not require 

 pipes so small as three-eighths of an inch in diameter, 

 therefore I used my smallest 1-inch pipes, and my mains were 



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