Of Chimney Fireplaces. 541 



just above the opening of the pot ; and most of the 

 caps which turn with the wind are not much better. One 

 of the most simple contrivances that can be made use 

 of, and which in most cases will be found to answer the 

 purpose intended as well or better than more com- 

 plicated machinery, is to cover the top of the chimney 

 with a hollow truncated pyramid or cone, the diameter 

 of which above, or opening for the passage of the 

 smoke, is about 10 or n inches. This pyramid, or 

 cone (for either will answer), should be of earthen- 

 ware or of cast-iron ; its perpendicular height may 

 be equal to the diameter of its opening above, and the 

 diameter of its opening below equal to three times its 

 height. It should be placed upon the top of the chim- 

 ney, and it may be contrived so as to make a handsome 

 finish to the brick-work. Where several flues come out 

 near each other, or in the same stack of chimneys, the 

 form of a pyramid will be better than that of a cone for 

 these covers. 



The intention of this contrivance is, that the winds 

 and eddies which strike against the oblique surface of 

 these covers may be reflected upwards, instead of blow- 

 ing down the chimney. The invention is by no means 

 new, but it has not hitherto been often put in practice. 

 As often as I have seen it tried, it has been found to be 

 of use; I cannot say, however, that I was ever obliged 

 to have recourse to it, or to any similar contrivance ; and 

 if I forbear to enlarge upon the subject of these inven- 

 tions, it is because I am persuaded that when 'chimneys . 

 are properly constructed in the neighbourhood of the fire- 

 place, little more will be necessary to be done at the top 

 of the chimney than to leave it open. 



I cannot conclude this essay without again recom- 



