1879 •] HEATING BY HOT WATER. 419 



" electric spavk," appear, " 1 have no doubt they will." The complete 

 sentence was : " This may appear to some to be curious reasoning ; 

 but all such people I refer to Mr Hammond's letter in your May 

 number in reply to Mr Inglis, and as he proves his position, while 

 others only assert, I have no doubt they will be satisfied." The 

 words as printed have no meaning apart from the context, while the 

 completed sentence explains itself. A. D. Makenzie. 



2 Grove Terrace, July 28, 1879. 



In your July issue your correspondent " C. M." says : " It is a well- 

 known fact that a house situated above the level of the others is the 

 hottest, from its having a quicker circulation." If he will call 

 upon us we will show him an exception to this rule. We have here 

 about 8500 feet of 4-inch pipes attached to two twin Climax boilers, 

 which, according to the statement of the makers, Messrs Barr & Sug- 

 den, are capable of heating 2200 feet more pipes than are attached to 

 them, so we may safely conclude they are capable of doing their 

 present quota of work with ease. The mains, flows, and returns, 

 which conduct heated water to our houses, have a direct run of about 

 326 feet, with a gradual rise from lowest to highest point of 13 feet. 

 The principal of the firm of Horticultural engineers who laid these 

 mains, examined the ground before beginning the work, and declared 

 the local conditions admirably adapted to a rapid circulation and a suc- 

 cessful termination of his labours. The work in its various stages was 

 superintended by no less than three practical hot-water engineers — an 

 accumulation of engineering skill which should have placed us in pos- 

 session of a favourable example of what one of your correspondents is 

 pleased to term the " old system of heating." We do not know of a 

 9-feet length of flow-pipe in our houses which has not at least J-inch 

 rise in its length, and of course the returns have precisely the same 

 descent to the mains. Every flow-pipe leading from the mains to each 

 of our houses is supplied with a valve so that the heat may be entirely 

 under control. 



It was implicitly believed, beyond all shadow of doubt, that 

 the pipes situated on the highest level, taken from the boiler, would 

 be so much the hottest, that valves were put on the mains at about 

 164 feet from the boilers, in order to check the expected natural in- 

 clination of the heated water to rush to the highest point, and so 

 neglect the houses on the lower levels, — so much for theory. The 

 actual results are directly opposed to the engineers, and, at the time, 

 our own " rule of thumb " ideas of the natural laws governing the cir- 

 culation of hot water. All the houses situated on the lowest level are 

 the hottest, so much so as to require the greatest nicety in managing 

 the valves, which have to be so nearly shut as to almost stop circu- 

 lation altogether. The houses, situated on what we may term the 



