The object of this paper is to investigate the Effect of fillet on the endurance of metal subjected to repeated stress. For this purpose, test pieces were cut out from one block of billet of Siemens-Martens' open-hearth steel and heat-treated in the same method, and then carefully finished into six different forms, i.e. to have six different sizes of fillet at the root of test pieces, the length of their plain part being made all equal. All the physical and chemical properties of the material were carefully observed. The test pieces were continuously rotated untill breaking by White-Souther Repeated bending tester. The results of the experiments show that the limitting stress to be allowed to each kind of the test pieces greatly depends upon the size of fillet and Summary of the results is : - [graph] In oder to clarify the state of the distribution of stresses in the locality where fillet is formed, photo-elastic method was adopted. For this optical experiment, six models of cantilever beam made of transparent celluloid plate were prepared and each having the radii of fillet corresponding to those of the test pieces. Of course, in this case, it can not be expected that the stress distribution is equal to that in the endurance test pieces, but the general behavior of stress distribution can be observed. By means of a comparison tester, made by the authors, the amount of stresses occuring in the several parts of the celluloid models were measured and shown in the paper. As the conclusion, the authors prefer to fix the radius of the profile of fillet as a certain division of the diameter or thickness of the body of the part and recommed to alter, if necessary, the usual forms of machine parts, which so long adopted without paying much attention about the Effect of fillet. For instance, as a result of enlarging the fillet at the root of teeth of a toothed wheel, a certain portion of the rim may be cut off leaving a deeper recess between the teeth and yet its endurance is thereby increased. For lengthening the life of a machine part, precaution must be taken so that the effect of fillet may not be disregarded, especially at the precent time, when most of the machines have a tendency to run at higher speeds.

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A new and simple method to detect some properties of the water flow is described in this paper. An ordinary photographic dry plate is put into contact with some lines of a developing solution in water flow. Thus the regions where steady flow, eddy current, or dead-water present may be distiguished.

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A formula for the efficiency of a locomotive boiler with superheater was deduced from the experimental results obtained at the Altoona Testing Plant of Pa. R. R. about six kinds of locomotives. The efficiency is expressed in terms of the rate of combustion and the ratio of the heating surface to the grate area. The efficiency formula for the saturated steam locomotive boiler was also obtained. The evaporation is expressed by the products of the rate of combustion, the grate area, the heat value of the coal used, the boiler efficiency and the inverse of the total heat of steam. This method of calculation enables us to obtain the evaporation under several service conditions, viz., several rates of combustion and several kinds of coal.

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