196 



Ma?iagemeni of Conical Boilers, 

 37 



and so much have they been in demand ever since, that Mr. 

 Douglas had orders for betwixt thirty and forty of them, of 

 which one was for Earl Gray, Howick Hall. 

 London, Dec. 1839. 



[The principles of construction exhibited in these gates may 

 afford suggestions for combinations of iron wires and rods, to 

 serve as skeleton roofing, upper flooring of cottages, and more 

 especially for fire-proof flooring and roofing. — Cond.~\ 



Art. VI. On the Management of Conical Boilers, toitk some Observ- 

 ations on the comparative Strength and Economy of different Kinds 

 of Fuel. By John Rogers, Jun,, F.R.S. F.H.S. 



In drawing up the description of the conical boilers, which 

 appeared in the Gardener's Magazine for the last month, I pur- 

 posely abstained from any minute details respecting fuel and 

 management. Some experiments in which I was then engaged, 

 on the comparative efficiency, as well as the relative economy, 

 of various kinds of fuel being now complete, I proceed to lay 

 the results of them before the public, premising my account 

 with a few words on the general management of the boilers, in 

 which, as the points touched upon are of material importance, I 

 must run the risk of a little repetition. 



In the first place, I wish it to be clearly understood, that no 

 caking or bituminous coal, or indeed any coal which produces 

 smoke, should ever be employed, except so far as a small quan- 

 tity of coal will always be found mixed with good cinders. 

 Partial inefficiency, or total failure, and an extreme waste, will 

 assuredly follow every attempt to use improper fuel; and cin- 

 ders, coke, or Welsh coal alone are suitable. 



In the next place, the chimney should not, except under 

 peculiar circumstances, exceed 5 ft. in height, nor should the 

 aperture of it exceed that of the top of the boiler : generally 

 speaking, a chimney of about 3 ft. in height will be found most 

 convenient. 



