1879.] HEATING BY HOT WATER. 421 



thinks so ; but I would hint, that possibly he is the only intelligent 

 reader of ' The Gardener ' who holds this opinion. From the first I 

 contended that the highest point of the apparatus should be as near 

 the boiler as possible, and not as far from the boiler as it can be got as 

 is the usual practice. Mr Makenzie now says it makes no difference 

 where the highest point is — not a shade of a difference. Is this proving 

 that I am " wrong fundamentally on almost every point " ? In my 

 humble opinion, it is granting what I contended for. I would also 

 point out that if it makes " not a shade of a difference " where the high- 

 est point is, then, as sure " as one and three make four " whether two 



and two does or does not — there is no necessity " in ninety-nine out of 

 every hundred cases " for sinking the bottom of the boiler more than 

 one foot below the floor-level on which the pipes are fixed. And there- 

 fore those " unmitigated nuisances," deep stock-holes, need no longer 

 exist. 



I would remark, however, that it makes all the difference, so far as 

 the rapidity of the circulation is concerned, at what point of the ap- 

 paratus the water attains to the highest point of elevation. If we want 

 the most perfect circulation attainable in any form of the apparatus 

 the water must ascend vertically from the point on which the fire acts 

 to the highest point. I could tell Mr Makenzie how to prove the truth 

 of this statement, but I will save space in ' The Gardener ' by giving a 

 quotation or two from one of Mr Makenzie's favourite authors, which 

 will perhaps be more satisfactory proof to Mr Makenzie that I am right 

 than anything I could advance in the same direction. 



Hood, on warming buildings by hot water, page 45, says : " It has 

 occasionally occurred that the circulation of the water in the apparatus 

 has been reversed, the hot water passing along what should be the re- 

 turn-pipe, and the colder water following the course of the flow-pipe. 

 This effect has sometimes been exceedingly puzzling ; but it will be 

 found to arise in those apparatus which have but small motive power 

 and in which the principle has not been followed out of making the 

 water rise to the highest point of the apparatus as soon as possible and 

 allowing it, in its return to the boiler, to give out its heat to the various 

 pipes, coils, or other distributing surfaces which it is intended to heat." 

 Again, at page 169, Hood says : "In all cases where pipes are placed 

 at various elevations above the boiler, for the purpose of warming 

 different floors of a building, or where, from any other cause, the pipes 

 descend by steps or gradations from a high to a lower elevation before 

 the water returns to the boiler, it is desirable that the water should be 

 made to ascend at once from the boiler to the highest elevation. By 

 this means the best possible circulation is always insured." I hope 

 these quotations will satisfy Mr Makenzie that it makes " a shade of a 

 difference " to the circulation atwhat point of the apparatus the greatest 

 elevation occurs. Mr Makenzie says he " will show that increasing the 

 vertical height and increasing the difference between the temperature of 



