U6 



ON CAS LIGHTS. 



Leaden pipes 

 preferable to 

 old gun bar- 

 rels. 



Secondly, I recommend the use of old gun barrels for 

 pipes: but since I wrote my former letter, I have been in- 

 duced in a great measure to change my mind ; for, having 

 been employed in putting up the apparatus for some per- 

 sons in this place, I find the promised advantage is not so 

 great as it first appears. Being in short lengths, they re- 

 quire many joints, or soldering places, and if they be not 

 properly sound and air-tight, the gas escapes, a disagreea- 

 ble smell is produced, your gas is wasted, and the process is 

 disliked. Now the patent lead pipe may be had in lengths 

 of fifteen or twenty feet, so that even in extensive manufac- 

 tories but few joints will be wanting. The pipes likewise 

 can be made three quarters of an inch or one inch in the 

 bore or hole, which is an advantage; you can bend them 

 round any angles ; and there will not be so great a proba- 

 bility of leakage, when there are but few joints. I think 

 therefore, although the lead pipes will be rather more ex- 

 pensive, yet when all their advantages are considered, it will 

 be better to adopt them, than the other. Besides, when 

 the pipes are done with, and a man gives over trade, or when 

 he removes his manufactory, he can very easily remove these 

 and put them up again, or sell them for a great part of the 

 original cost for old lead. There is also another saving in the 

 workman's putting up the apparatus, as he puts up the lead 

 pipes in half the time he would the old gun barrels. 



Perhaps therefore we may make the following statement, 

 for in fact it will be in general the true statement, where 

 only lights are wanting for twenty weeks in the year. 



Dr. 



Cr. 



Corrected 

 statement. 



Coal for twenty 



weeks, at Is. 3d I 5 

 Interest on £20 or 



25 ..•• 1 5 



Saved 16 2 6 



£18 12 6 



Twenty weeks, at 



is.Sd, 18 



Coak 12 6 



£18 12 6 



Here I have only allowed the half of my former statement 

 for the expense of coal, supposing no soldering is done, for in 



that 



