In order to secure the safety of rails in service track, it is necessary, first, to know accurately the rail stress caused by external load. For this purpose, an experimental observation was made by two and three dimensional photo-elasticity so as to make a fundamental study on the stress distribution of the rail section under various loads and boundary conditions such as the state of concentration or distribution of local stress.

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a. The Author composed the equation of the joint impact of track rails. According to several results of his experiments, this equation have been available substantially.
b. He obtained the relations between joint impact, sorts of vehicles and its velocities.
c. He cleared the behaviour of joint impact.
d. The pressure gage which he designed and used for this study, have been effective in spite of its simple mechanism.

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As an essential subject for the sake of treating theoretically the problem of sediment transport under the tractive force on the bed of river, it is very important to clarify the mechanism of the formation of sand ripples on the bed in the case of bed-load transportation. In other words, it is necessary to know how sand ripples occur and develop according as the condition of flow and the properties of bed sediment. As a fundamental research for this purpose, the writer experimentally mad clear the flow phenomena of bed load movement by using the sand bed without ripples, at the states such as the sand ripples were not yet occurred on the bed or the ripples were hardly generated in the case of using some kind of sands and theoretically analysed the results obtained. Finally he obtained the following conculusions.
(1) Near the critical tractive force, the bed load movement is able to be treated as a kind of fluid motion, and under such way of thinking the writer introduced the formulas concerning the sediment transport in the case where the ripples were not generated. From the results obtained by using the formulas it can be said that the rate of sediment transport under the tractive force near the critical limit show some widely aport tendency According to the grain size of sand composing the channel bed.
(2) The effect of ripple on the rate of sediment transport is quite different whether thee grain size of the sand constituting the channel bed is larger or smaller as compared with the critical size of 0.075cm in diameter. And, furthermore, the sand the size of which is near this critical diameter is easily to be moved owing to the characteristics belonging to the sand itself.

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The object of this paper is to clarify functions of the level apron with upward water jet from the bed, which accelerates the hydraulic jump of supercritical flow on the level apron.
For this purpose, the author introduces the jump equation for this type of apron by momentum theory. The results of a model test on this special energy dissipator show the close agreement with the values computed by the author's formulas, and also give some experimental formulas.

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In studying the mechanism of water erosion of land-surfaces by rain water flow, it is necessary to evaluate experimentally the relations between the factors related to the phenomena of soil detachment from land-surfaces and transportation of detached soil. In this paper, erosion of land-surfaces consisting of sand or sandy soil by stream flow is treated. For this approach, hourly variations of the rate of detachment of soil, the discharge of surface flow and grain diameters of transported soil, and rates of sediment transportation by rain water flow are measured. The experimental results are discussed comparing with those obtained by some authorities. Moreover, a dimensionless expression on the rates of detachment of soil is proposed.

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This paper indicates the many factors to influence on the effective width of steel plate floor as the flange of main girder of the 2-steel plate girder type bridge with orthotropic steel plate floors and describes a theoretical method of determining it by setting the some statical assumptions, and proposes to carry out the calculation for design of the bridge of this type using the above-mentioned effective width.

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Beams with elastic supports have many interesting problems for the mathematical analysis. One of these solutions is described in this paper concerned much with the vibrational problems. The proper vibrations of a system of the beam attached with material points show orthogonarities each other in the elastic energy of beams. Affine-Forces are defined to solve continuous beams with springs like such forces as are acting at the elastic gravity point.

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