A number of flues concentrated, forms a stack of chimneys, as represented in the engraving. Flues, at a distance from the stack, are conveyed to it either in a horizontal or sloping form, as at A and G. The size of flues generally is nine inches by fourteen inches; a space sufficiently large to convey the smoke, but not large enough to be ascended, except by little children, for the purpose of cleansing them. The plan adopted by the climbing-boy to ascend chimneys is, by pressing his feet, back, and knees against the sides of the flue, by which means he propels or hitches himself up by degrees, having one arm above his head, holding a brush, and the other arm by his side, as described in B. At C the boy is represented as putting his brush out of the top of the chimney-pot, but generally he rattles it with his brush, to satisfy the parties below that he has been to the top. This accomplished, he gradually slides down to the stove or grate. It has frequently occurred, that boys have, either through fear or inattention, got into the form of nose and knees together, as described at E; sometimes they remain in this cramped and painful position for hours before they are liberated, being totally unable to extricate themselves. Climbing-boys are exposed to considerable danger in horizontal or angular flues, as at A. The reason is obvious; after passing through the chimney and descending to the second angle from the fire place, the boy finds it completely filled up with soot, which he has dislodged from the sides of the upright part. He endeavours to pass by it, and after much struggling, he succeeds till stopped by his shoulders; but the soot is compressed so hard all around him, by his exertions, that he cannot go back; he then endeavours to move forward, but his attempts in this respect are often useless, for the covering of the horizontal part of the flue being stone, the sharp angle of it bears hard on his shoulders, as at H, and prevents him from moving in the least either one way or the other. His face being covered with a climbing-cap, and being completely enclosed in the soot beneath, his breath is stopped. In this dreadful condition he struggles violently to extricate himself, but his strength fails him, and in a few minutes he is gone for ever. Many instances have occurred of boys being thus suffocated in chimneys, or burnt, or smothered in the rubbish, while attempting to core a chimney; others have been killed by falling from the tops of chimneys. Such accidents have happened in London, Edinburgh, Dublin, Waterford, Wakefield, Newport Isle of Wight, Hereford, Preston, Dumfries, Dudley, Deal, Keighley, Clapham, and Belfast; and many other cases may have occurred without having come to the knowledge of the public. [Illustration]