Mode of heating hy hot Water. 205 



300 degrees of heat, it is only necessary to resist a pressure 

 of 60 lbs. or 70 lbs. to the square inch, it must be evident 

 that there is sufficient room allowed for any thing extraordi- 

 nary in the way of pressure. All the care that is necessary 

 to make my apparatus perfectly secure against such accidents 

 is, to prove it with a common hydraulic pump the last thing 

 before setting it to work. 



As some of my pipes have burst, and one, in particular, at 

 the Guardian Fire Office, I think it right to explain how 

 that occurred. When my apparatus was first erected in that 

 office, which was last winter, the building was not finished ; 

 and the workmen, being anxious to dry the walls of the new 

 building, set the apparatus at work before it was proved : and 

 as it is almost impossible, in 1000 ft. of pipe, to make every 

 thing perfect at first, so it was in this case; for, in giving the 

 fire an unusual draught, the heat of the pipes was increased to 

 an unprecedented extent; and the consequence was, that a 

 pipe split in one of the empty rooms, and made a slit in the 

 seam of the pipe about 6 in. long, and an eighth of an inch 

 wide. Another pipe was immediately put in, and the ap- 

 paratus proved : it has been at work ever since, to the perfect 

 satisfaction of the committee. 



This defect would be a serious evil, if I had not the means 

 of remedying it by using stronger tubes, and having all my 

 apparatus proved (previously to using) by the hydraulic press. 



So confident am I now of the perfect safety of my appara- 

 tus, that I am ready to trust its erection to gardeners them- 

 selves ; and have made arrangements for sending, to any part 

 of the country, coils and tubes, with ample printed directions 

 for erecting them, and managing them afterwards. This will 

 reduce the cost of a hot-water apparatus to its minimum. 



I am. Sir, yours, &c. 

 21. Great Coram Street^ Russell Square, A. M. Perkins. 



Feb. 3. 1833. 



The above is a most important communication ; and we are 

 sincerely glad that the doubts which we threw out, in the note 

 alluded to by Mr. Perkins, have elicited from that gentleman 

 arguments so satisfactory, in proof of the fact that, as it is 

 impossible for any deposit of matter held in solution by water 

 to take place without evaporation, none can be deposited in 

 his hermetically sealed tubes. — Cond. 



The following is the letter referred to by Mr. Perkins, and 

 addressed to him by Mr. Carpmael : — 



" Dear Sir, — In answer to your enquiries respecting my 

 having burst a boiler about two years ago, I now send you a 



