The enormous waste of fuel in London may be estimated by the vast dark cloud which continually hangs over this great metropolis, and frequently overshadows the whole country, far and wide; for this dense cloud is certainly composed almost entirely of UNCONSUMED COAL, which having stolen wings from the innumerable fires of this great city has escaped by the Chimnies, and continues to sail about in the air, till having lost the heat which gave it volatility, it falls in a dry shower of extremely fine black dust to the ground, obscuring the atmosphere in its descent, and frequently changing the brightest day into more than Egyptian darkness. I never view from a distance, as I come into town, this black cloud which hangs over London, without wishing to be able to compute the immense number of chaldrons of coals of which it is composed; for could this be ascertained, I am persuaded so striking a fact would awaken the curiosity, and excite the astonishment of all ranks of the inhabitants; and PERHAPS turn their minds to an object of economy to which they have hitherto paid little attention. Conclusion. Though the saving of fuel which will result from the improvements in the forms of CHIMNEY FIRE-PLACES here recommended will be very considerable, yet I hope to be able to show in a future Essay, that still greater savings may be made, and more important advantages derived from the introduction of improvements I shall propose in KITCHEN FIRE-PLACES. I hope likewise to be able to show in an Essay on COTTAGE FIRE-PLACES, which I am now preparing for publication, that THREE QUARTERS, at least, of the fuel which cottagers now consume in cooking their victuals, and in warming their dwellings, may with great ease, and without any expensive apparatus, be saved. END OF THE FOURTH ESSAY. EXPLANATION OF THE FIGURES [ IMAGE ] Fig. 1. The plan of a Fire-place on the common construction. A B, the opening of the Fire-place in front. C D, the back of the Fire-place. A C and B D, the covings. See page 341. [ IMAGE ] Fig. 2. This figure shows the elevation, or front view of a Fire-place on the common construction. See page 341. [ IMAGE ] Fig. 3. This Figure shows how the Fire-place represented by the Fig. 1, is to be altered in order to its being improved. A B is the opening in front,--C D, the back, and A C and B D, the covings of the Fire-place in its original state. a b, its opening in front,--i k, its back,--and a i and b k, its covings after it has been altered, e is a point upon the hearth upon which a plum suspended from the middle of the upper part of the breast of the Chimney falls. The situation for the new back is ascertained by taking the line e f equal to four inches. The new back and covings are represented as being built of bricks;--and the space between these and the old back and covings as being filled up with rubbish. See page 342. [ IMAGE ]