"Where the top of a Chimney is commanded by high buildings, by clifts, or by high grounds, it will frequently happen, in windy weather, that the eddies formed in the atmosphere by these obstacles will blow down the Chimney, and beat down the Smoke into the room.—This it is true will be much less likely to happen when the throat of the Chimney is contracted and properly formed than when it is left quite open, and the Fire-place badly constructed; but... 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 complicated 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 11 inches. ...[I]ts 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 Chimney, and it may be contrived so as to make a handsome finish to the brickwork."