Identifier: machineryprocess00barn (find matches)
Title: Machinery and processes of the industrial arts, and apparatus of the exact sciences
Year: 1869 (1860s)
Authors: Barnard, Frederick A. P. (Frederick Augustus Porter), 1809-1889
Subjects: Machinery Scientific apparatus and instruments
Publisher: Washington, Govt. print. off.
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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,and the articles are more gradually heated and more gradually cooled.There is no smoke generated, and the fuel is burnt while falling bygravity to the bottom of the furnace. Such furnaces are useful forroasting ores or cement, or for baking fine pottery, as well as for burn-ing bricks. Another advantage consists in the fact that the progress of the oper-ation may be easily inspected in all parts of the mass exposed to the heatwhile it is going on, and the degree of heat may be increased or dimin-ished at pleasure, preventing any danger of injury or loss from over-burning or from under-burning. These furnaces are likely to come largely into use in manufacturingornamental terra cottas for house fronts, as in cornices, friezes and lin-tels, as well as for statues, vases, fountains, &c, to be used as rusticembellishments of landscape gardening. The statement of the inventor that the saving amounts to two-thirdsin respect to fuel is confirmed by the results of experience in the use of
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ECONOMY OF HOFFMANS ANNULAR BRICK FURNACE. 359 the Hoffmann furnaces in England. From these it appears that thesaving is even greater than he claims. At the works of Mr. Betty, atKensington, the following represents the comparative cost to the pro-prietor of brick per thousand, by the old and new methods of burning.These numbers are given in the Practical Mechanics Journal of October1, 1865, by the superintendent of the works: Cost of-production of one thousand brick. Old brick-kilns. Hoffmann furnaces. For wages £0 Is. 6d, £0 Os. M. For coal, 10 cwt 7 10£ 2 cwt. 1 7 For loss 1 0 Total 10 U =$2 50 2 1 =$0 50 Giving a ratio of economy as one to five. The following is the result of observations made at Durham by Mr.G. Furness: Comparative cost of production of 222,000 brick in old-fashioned Scotchbrick-kilns and in Hoffmanns furnaces. Scotch furnaces—17 tons 14 cwt., at 15s. the ton £59 15s. 5tf,=$289 29 Hoffmanns furnaces—27 tons 12 cwt., at 12s. 6d.the ton 17 5 0 = 84 70 Diffe

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