ERRATA. The following corrections in the article The Decimal Gauge in the last number of the JOURNAL should be made: Page 383, line 5, read "the second increase of successively." Page 385, line 5, read "R= (1 + 0·003824t+ 0·00000126 f2)" By inadvertence, credit for Mr. J. H. Cooper's article "On the Adhesion of Belts" in the June number was not given to the Journal of Commerce, of Boston, in which a considerable portion of it first appeared. THE Franklin Institute is not responsible for the statements and opinions advanced by contributors to the JOURNAL. THE BELT DYNAMOMETER OF DOCTOR C. W. SIEMENS. By ROBT. BRIGGS, C.E. The accompanying illustration of a belt dynamometer after the general design employed in experiments with the Siemens dynamo-electric machine, has been prepared by the writer of this article, to meet the demand for a more quiet and equally reliable instrument of this kind than is found in the well-known geared or tooth-wheel dynamometer in common use in this country. The principle involved in the construction of this dynamometer,. that is, the weighing of the resulting stress from a deflected cord or band, and thus ascertaining the direct stress upon the band itself, is not new. This was one of the carliest methods of measuring the load. upon a telegraphic cable when paying out, and it is believed that the method has been applied for a dynamometer in Germany for some time, but the attention of the writer was first brought to it by perusal of the paper of Messrs. Higgs and Brittle on Electrical Apparatus, in the Proceedings of the Institution of Civil Engineers for 1878. The illustration in that paper was sufficiently good for any mechanic to work out a practical machine, using the general details of shafting and pulleys of American practice, and the only improvement or novelty now presented consists in thus adapting the machine of Dr. Siemens to American convenience. WHOLE NO. VOL. CX.-(THIRD SERIES, Vol. lxxx.) 1 403431 |