38 ANNUAL OF SCIENTIFIC DISCOVERY. 



A considerable saving in the cost of engraving the Ordnance Maps is effected 

 by using steel punches to cut the woods, figures, rocks, etc., on the copper 

 plates ; the work is thus done much more quickly than by hand, and boys 

 are employed at it in the place of skilled engravers. A portion of the writ- 

 ing, also, on the copper plates, is engraved by machine (Becker's patent), 

 and the parks and sands are ruled by a machine with a steel dotting-wheel, 

 the pressure of the wheel and the interval between the dots being regulated 

 according to the tint required to be produced. The ink used in the copper- 

 plate printing consists of Frankfort black with a mixture of Prussian blue, 

 ground with burnt oil in a mill constructed at the Ordnance Map Office, at 

 Southampton, for the purpose. After printing, the impressions are first 

 dried between millboards, and are then placed between glazeboards, and 

 pressed in an hydraulic press, after which they are ready to issue. London 

 Times. 



RAILROAD AXLES AND THE FORCES THEY HAVE TO RESIST. 



v 



From a Prussian journal for architects and civil engineers, we derive the 

 following report of a series of experiments, made by Superintendent Woehler, 

 of one of the largest railroad lines in Prussia, with different axles, and under 

 different circumstances. 



The forces which act on these axles may be divided into two classes, one 

 class containing those forces which tend to effect a flexion or bending of the 

 axle, and the other containing those which effect a torsion or twisting of the 

 same. Two simple and ingenious apparatuses were attached to the axles, 

 which, by means of steel points acting against zinc plates, indicated, after 

 each trip, the degree of flexion and the respective torsion of the axle. 



With the experiments on the flexion of the axles, it was necessary to as- 

 certain that force which, when applied to the circumference of the wheel, 

 corresponds to the flexion indicated by the steel point of the apparatus on 

 the dial-plate. For this purpose two dynamometers are attached, one to each 

 wheel and near to its circumference, and the two wheels are forced towards 

 each other, until the apparatus on the axle indicates the same degree of flec- 

 tion which has been indicated by the steel point during the trip. It must, 

 however, be remarked, that the apparatus, as it revolves with the axles, causes 

 the index to deflect in opposite directions, producing a deflection twice as large 

 as that produced with equal power by means of the dynamometer. The ap- 

 paratus was so constructed that, during the motion of the train, one inch 

 deflection of the index was equal to a side motion of the circumference of 

 the wheel of 3-16 of an inch, or to a deflection of 3-32 from its normal position. 

 The side-draught, which has to be applied to the circumference of the wheel 

 in order to produce the same flection of the axle, or a one-sided deflection of 

 the index of a half inch, is equal to 23i cwt. for axles of 3f inches diameter 

 in the hubs, and for wheels of 36! inches diameter. For axles of 5 inches 

 diameter in the hub, and with wheels of 36f inches, the side-draught was 

 found to be 70 cwt. 



With the experiments on torsion the apparatus was so constructed that, 

 with axles of 3? inches, one inch deflection of the index corresponds to a 

 motion of 0'3^1 inches on the circumference of awheel of 36| inches, which 

 is also the double amount of the real deflection of each point of the circum- 

 ference from its normal position. Each inch of deflection of the index, 

 therefore, corresponds to an angle of torsion of 30 minutes. To produce 



