Whilst upon this subject, we have great pleasure in calling the attention of our readers to a very effective machine for sweeping chimneys, invented by Mr. Glass, which has been approved by the Society for Superseding the Necessity of Climbing Boys, and which seems applicable to almost every con struction of flues. The brush, Fig. 1, is made of a round stock a, commonly alder, and pierced with small holes, into which bunches, formed of strips of the best whalebone, are inserted and fastened by glue. These strips b are from 8 to 84 inches in length, which renders the brush, including the stock, about 20 inches in diameter ; it therefore completely fills, and effectually cleanses, the largest flues, which are never more than 14 inches square, and are seldom more than 14 by 9 inches. At the end of the stock c is a very strong brass ferrule, with a wormed socket, which receives the screw of the first joint. Fig. 2 is a representation of the ferrules of the real size ; the three first portions d d d, 21 feet in length, are made of good cane, the rest e e e of ground ash, and of the same length, the number used of course depending upon the height of the chimney ; these are made gradually stronger towards the bottom, and are affixed to each other by means of the brass screws and sockets in Fig. 2, before described. The superiority of this machine consists in extreme pliability, lightness, and strength, which render it peculiarly applicable in high chimneys having a diagonal portion at b, as shown in the annexed Fig. 3. If Glass's machine be introduced through B, it will proceed to the top of A with ease, whilst most other machines generally stick at b. A common defect in the construction of chimneys, although not so great in houses of recent construction, is, that the aperture is generally much larger than necessary for the passage of the smoke, the consequence of which is, that the fuel in the grate not being sufficient to rarefy the whole portion of the air in the flue, the rising current of heated air is met by a descending current of cold air, and the smoke is borne back into the room. By Mr. Tredgold's rule, before given, it appears, for a grate 18 inches wide, a chimney 36 feet in height would require an aperture of only 51 inches area, little more than 7 inches square, whereas no chimneys are less than 14 inches by 9. It is true that they could not be swept by climbing boys if made of less dimensions; but if carried up in nearly a straight direction, without abrupt bends, they might be easily cleaned by machinery, by which means a barbarous and inhuman practice would be abolished, and the proper dimensions being assigned to the chimney, the annoyance of smoke in the apartments would be got rid of. The most effectual remedy for smoky chimneys is to
contract the aperture, and lower the breast of the chimney; and when this has been carried as far as is practicable, some further benefit may be derived by placing on the summit a revolving cap, turned by a vane, so that the aperture for the smoke shall always be to leeward.
A machine of this description, invented by Capt. Halliday, is represented in the engraving on the preceding page. a and b are two square plates of iron, or other metal, the upper one being supported by four vertical pillars ; c is the aperture for the passage of the smoke from the brick flue immediately beneath ; across this aperture a bar is fixed horizontally, sup porting the upright spindle d, on the upper end of which is fixed a double-tailed vane, shown in plan at Fig. 2. Below the plate a square plate, forming a screen or guard, is attached by braces to the spindle, and the spindle being turned by the action of the wind upon the vane, the screen is constantly opposed directly to the wind.
sketch below exhibits a smoke cowl commonly used at Glasgow : — Fig. 1 is an elevation, and Fig. 2 a plan or horizontal section of the contrivance, which consists of a quadrangular box of sheet iron, surmounted by a pyramidical cap, and placed, as exhi bited, over the top of the brick flue. There are four doors to it, abed; a is connected by an intermediate rod f to the opposite door c, and b, by the rod e to the door d, so that when the wind closes the door opposed to it, the opposite one is opened for the smoke to escape uninfluenced by the wind.
The annexed engraving represents Mr. Fen ner's apparatus for curing smoky chimneys. It consists of a spiral tube or flue to the upper part of an ordinary chimney. These tubes are made of thin copper, and furnished with a flange at the lowest end upon which it rests on the top of the brick-work of the ordinary flue. The chimney is then continued upwards with a reduced thickness of brick-work, by which means the capacity is sufficiently enlarged for the reception of the spiral tube. The expanded part of the chimney is closed in at top so as to form a hot-air chamber round the tube, which being of thin metal, the heat is readily transmitted to the chamber.