170 Advertisement. 



I have, indeed, of late seen but too many proofs 

 of the necessity of adopting this cautious method of 

 proceeding. 



On my return to England from Bavaria last autumn 

 (1798), after an absence of two years, I was not a little 

 gratified to learn that several improvements recom- 

 mended in my Essays, and particularly the alterations in 

 the construction of chimney fire-places, that were pro- 

 posed in my fourth Essay, had been adopted in many 

 places, and that they had in general been found to 

 answer very well ; but the satisfaction which this infor- 

 mation naturally afforded me has since been, I believe 

 I may say, more than counterbalanced by the pain I 

 have experienced on discovering, on a nearer examina- 

 tion, the numerous mistakes that have been committed by 

 those who have undertaken to put my plans in execution ; 

 not to mention the unjustifiable use that has in some 

 instances been made of my name in bringing fonvard 

 for sale inventions which I never recommended, and 

 of which I never can approve without abandoning all 

 the fundamental principles relative to the combustion 

 of fuel, and the management and direction of heat, 

 which, after a long and patient investigation, I have 

 been induced to adopt. 



It would be foolish for me to imagine, and ridiculous 

 to pretend, that the plans I have proposed are so per- 

 fect as to be incapable of farther improvement. I am 

 far, very far, from being of that opinion, and I can say 

 with truth that I shall at all times rejoice when farther 

 improvements are made in them; but still I may be 

 permitted to add that it would be a great satisfaction 

 to me if those who, from an opinion of their utility or 

 from a desire to give the experiment a fair trial, should 



