WIENER KALK:—The Horoiogical Journal states that the material generally used by watchmakers on the continent for polishing hard and soft steel, as well as brass, is a white substance called wiener kalk; it polishes much quicker than crocus, and with a beautiful black gloss. It is used in the following manner: The piece to be polished is first put on a piece of cork fastened in the vice and rubbed with a piece of plate glass, on which is put a little oil and oilstone dust, till it is perfectly fiat and all the file marks have disappeared. It is then cleaned with a brush and soap and water, and dipped in spirits of wine, and, after being dried with a clean cloth, put on another clean piece of cork, in the same way as before, and rubbed briskly with a flat polisher, made either of bell metal or block tin, in which is put a little wiener kalk and fine oil, mixed to the consistency of a thick paste. It is necessary to prevent any dust getting in the polishing stuff or on the piece to be polished. Wiener kalk can be had at Mr. Ehn'hu- us' watchmakers' tools and materials warehouse, in Frith street, Soho square, London, where it is sold under tho nauio of diamantine, and perhaps at some of the tool shops in Clerkenwell. THE BAKER'S OVEN THERMOMETER.'This useful instrument for indicating- the temperature of an oven, is the invention of Mr. J. Bailey, of Salford. Bakers have hitherto generally baked bread satisfactorily ; nevertheless, housekeepers know that sometimes the bread is slack baked, while at others it is burnt; the fact being that the bakers judge the right heat of their ovens hy the appearance only, and, as a consequence, they must sometimes be deceived ; but by tho use of a proper thermometer (heat measure) no error can well occur. This instrument is also useful to the japanncr and others who use ovens and pottery furnaces.S. Piessc. WE learn from the London Mining Journal that England has sent more locomotives to Russia, Egypt, and Australia this year than heretofore, but in many other directions thero has been a falling off. In August, steam engines were exported from the United Kingdom to the value of only £ 169,495, as compared with £189,639 in August, 1868, and £187,781 in August, 1867. In the eight months ending August 31, this year, were exported, however, the aggregate value of £1,128,541 , as compared with £1,075,685 in the corresponding period of 1868. THERE is a papier-mache church, says the Churchman, actually existing near Bergen, Germany, which can contain nearly 1,000 persons. It is circular within, octagonal without. The relievos outside, and statues within ; the roof, the ceiling, the corinthians capitals, are all papier-macM, rendered water-proof by a saturation in vitriol, lime-water, whey, or the whites of eggs. As tallow-melters, oil-boileis, varnish-makers, and others, ?re very liable to accidents by fire, Dr. Piesse suggests to them the application of Sir Humphrey Davy's discovery of wire gauze, as in the miner's lamp, for the prevention of accidents, by covering the boilers and vats during operation with a drum-head or dome of wire gauze. HEMMING SEAMLESS BAGS.A correspondent complains that it is a common fault to hem seamless bags with a single- thread machine, and that the thread breaks, the hem. speeti- ly unravels, the bag cannot be securely tied, and its contents get wasted in handling, and asks why the lock-stich is not employed in the hemming of such bags. Will manufacturers answer why ? PETROLEUM oil, such as is used for lamps, is an effectual preventive against the destructive propensities of worms in timber. The timber is to be washed over with it.