i879-] HEATING BY HOT WATER. 525 



HEATING BY HOT WATER. 



Notwithstanding the editorial note at the end of the papers on the 

 above subject in the September issue of ' The Gardener,' I ask room for 

 the following remarks. I would not have made this request if Mr 

 Makenzie in his last paper had not attributed to me assertions which 

 I have not asserted, and assumptions which I have not assumed, at any 

 time during the controversy. 



I have not at any point in the discussion " asserted that a vertical 

 rise is a hindrance to the circulation, and is the cause of repeated 

 failures in the working of hot-water apparatus." On the contrary, I 

 assert that the highest point of the apparatus should be reached by a 

 vertical pipe out of the top of the boiler ; and that when the heated 

 volumes of water have to reach the highest point by travelling up a 

 slow gradient of hundreds of feet in length, the result is a return cur- 

 rent in the flows, which is a hindrance to circulation, and the cause of 

 an immense amount of heat being wasted in the stoke-hole. 



Mr Makenzie admits " that there is no necessity for the pipes having 

 a continuous ascent." Then why is it that in 999 cases out of 1000 

 they are fixed in this way 1 And why does Mr Makenzie advise us to 

 have our stoke-holes as deep as practicable 1 There being no necessity 

 for a continuous ascent of the piping, there is no necessity for a deep 

 stoke-hole. 



I have not, at any time during the discussion, asked Mr Makenzie 

 " if the upper strata in the flow-pipe travels faster than the lower 

 strata." This is what I asked — Does the upper and hotter stratum 

 travel faster than the under and colder stratum on the downhill 

 journey 1 And if not, why not ] And I again, for the third and last 

 time, respectfully ask the same question. I have not, at any time 

 during the discussion, assumed that the mere fact of water becoming 

 hotter " makes it fly away from the earth." The heated water would 

 remain in the boiler if colder water did not come in contact with it. 

 The colder being of greater density than the hotter, moves towards the 

 lowest place ; and the hotter being of less density than the colder, 

 moves towards the highest place. The movements of both are move- 

 ments in obedience to the law of gravitation, in accordance with their 

 respective specific gravities or densities. This fact I pointed out in 

 ' The Gardener ' of February last ; and what I have been contending 

 for since is, that the apparatus should be fitted up in such a way 

 that at all points thereof the volume of water therein will move of its 

 own accord in the right direction, in obedience to the law of gravita- 

 tion, and not have to be forced by the succeeding, or drawn by the 

 preceding, volume in that direction. Mr Makenzie invites us to 

 " come and see water at 80° forcing water at 60° uphill." Now, sup- 

 pose we did see water at 80° forcing water at 60° uphill, we would only 

 have an ocular demonstration that the apparatus in which this took 



