Many researches about the pressure resistance of the gliding plate on the surface of water have been published by various authors. Their method used may however be devided in two kinds of approximation in general. One is the method by which only the wave making ressistance of the plate is obtained, and the other is that of simplifying the problem by neglecting the gravitational force. The results obtained are quite dffierent in each other. The resistance by the latter method and the wave resistance by the former one are not the same thing, but, in actual both appear at the same time.
Now the writer investigated the notion of water under the gravity by using Lambs theory, considering a certain pressure distribution applied on the surface of water. It was discovered that in this theory the emergence of the sprash at the leading edge can be expressed by the singularity of the pressure distribution at this point, and due to this singularity a resistance other than that of wave making exists and is the very resistance obtained by the method of neglecting gravity. This resistance named sprash resistance occupies most part of the pressure resistance at high Froude number, while the wave resistance becomes small quantity.
The variation of the wave resistance due to the change in the shape of the plate is comparatively small, but the sprash reisstance receives a great effect, and it can be concluded that the camber of the plate generally reduces the sprash resistance.

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Aiming at the simplification of the process in working-up the shell plating of a vessel, the authors investigate the possibility in applying the developable surface-especially the tangent surface-to the forward and after parts of the shell plating, and sacceed in obtaining a general method to get proper lines of a simplified hull form satisfying requirements in W. L. and prismatic curves for the loaded condition. Such a new simplified hull form is expected not only to save time, labour and cost in shipbuildig but also to keep excellent characters in resistance, propulsion and seaworthyness. An example of such a simplfied hull form and the results of towing experiments at the model basin are shown in detail.

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Now in Japan small passenger ships are under contemplation. But owing to the construction in a great hurry it is quite impossible to perform the model experiments by each of them. While as far as I know, for such fine and small passenger ships, there are few model experiments reliable to use. Therefore heintended to study the propulsive performances of this sort of ships by the model experiments, and nowadays they are under experiment in our experimental tank.
In this paper a part of the above experiments already completed ae treated as the first report.

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About the longitudinal stability of a high speed boat in still water, Perring and others researched. In this paper the longitudinal motion among waves is adopted when it moves at right angle to wave lines, and the conditions not jumping above waves are researched. It means that the higher wave height is the more unstable a boat becomes and when wave height tends to zero, namely still water, it is stable surely. Also where the boat velocity is equal to the wave velocity, the boat position to the wave surface is constant, so no jump. The resistance derivatives used in it are introduced from the results of Sottorf's experiments and the stability of a single step boat is discussed. By those resistance derivatives the longitudinal stability of actual boats among waves is calculated.

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Mr. A. W. Johns states in the T. I. N. A. of 1907 that stress induced by centrifugal force T originating in unbalance of propeller is greatest and gives the value of the maximum bending moment at that time, but in this paper, the value of the bending moment is scrutinized a little further, and farthermore, the value of the twisting moment, shearing force, and normal force is examind. If the various dimensions are taken as given in the annexed figures. In ordinary ships l₂ is severa times or more than l₁ or 1, and L is several times or more larger than a. Furthermore, granting that conditions is between about 50 degrees and 90 degrees are generally substantiated, at such times, the stress due to twisting moment, shearing force, and normal force are negligibly small in comparnson to the stress due to bending moment. When T indicates certain direction the bending moment enlarges at the barrel part, but when the direction a changes it enlarges at the root. However its maximum value is induced in the barrel edge of the bracket, and its value, M_I, is determined by the following formula;
M_I=-Tlc₁cosα/(1+Kc₂c)sinθ
where
K=E₀I₀L/EI₁l
c₁=3ll₁²+6ll₂²+12ll₁l₂+4l₁²l₂+3l₁l₂²/2ll₂(4l₁+3l₂)
c₂=6l(l₁+2l₂)/l₂(4l₁+3l₂)
c=1/8sin²θ{5cos²(0-α)-6cosα
×cos(θ-α)+5cos²α}
E₀ & I₀…Young's modulus of shaft &
moment of inertia of the section.
E & I₁… … shaft bracket & _??_.
L, l, l₁, l₂, α, θ & α…the values given
in the annexed figures.
Value of α in the aforementioned formula is determined by the following formula;
Ncos²α/sinα=1/sin(θ-α)
where
N=2(3-5cosθ)/(8/Kc₂+5sin²θ

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The stress distribution in the orthogonal aeolotropic plate with a circular hole, when stretched uniformly along the axis of elasttc symmetry, has been analysed by Prof. Ikeda under the assumption that a certain relation existed among the elastic constants of the plate. In this paper the writer gives a more general solution of this problem without impos ng any restriction on the value of the elastic constants. Special simple expressions of the stresses on the circumference of the hole are deduced for the practical calculatin.

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In this paper the distribution of the stress and strain along the long plastic column under axial shock type load were investigated theoretically with some aid of experiments using plastic material such lead bar. In this theoretcial calculation, following assumptions have been used in the relation between dynamical stress and strain when the column is subjected to the axial shock type load: 1. The impact stress is represents by the sum of the stress proportional to the strain and the stress proportional to the straining speed wh ch produced by the impact, and the relat ons are preserves up to the column has buckled. 2. The elastic deformation is of little importance compared to the plastic deformatoin.
The results obtained by the investgations are as follows: 1. The mode of the plastic deformation and the stress destribut on along the column under axial impact have been shown by hyperbolic express ons.2. Additional stress proportional to the straining speed has been obtained as the coefficient of viscosity in the plastic range. 3. The ratio of shock type stress and strain which correspond to the Young's modulus were obtained as the parameters of straining speed of the element of the column, 4. The stress strdin diagram in the case of impact loading were obtained as the transition curve across a point of different stress-strain curves which obtained as the parameter of straining speed.

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As the preventive measure against the vibrations that occur often in various parts of ship construction, we have, first of all, to estimate accurately the frequencies and modes of the natural vibration of the structure as well as those of the forced one. For this purpose the writer developed a new method of calculation of the natural frequencies and modes of a vibrating plane-panel, stiffened by any number of parallel beams, and of the amplitudes of the forced vibration of the same structure under pulsating loads. Our method, described in this paper, is a simple mechanical procedure, with sufficient accuracy making use of formulae similar to those given in the slope-deflecion equations of structural mechanics, under the conditions that the plate edges perpendicular to the stiffeners are supported freely and the other edges left arbitrarily. It is also shown that some other cases under different boundary conditions may be treated in similar manner approximately.

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The naval architects have long been convinced that the position of engine should be located at the node of the free vibration of ship to make minimum the flexural vibration which is excited by the unbalanced forces of that engine. On the contrary, Dr, Sezawa proposed few years ago a new theory as the result of theoretical consideration that the position of engine should be located at the loop instead of the node of the free vibration of ship when the engine has the unbalanced forces and is located at the node when the unbalanced couple exists in the engine.
The authors have treated the problem theoretically to make clear which position should be selected in the design so as to reduce the flexural vibration as possibie.
According to our investigation, we find that there are some incorrect assumptions in Dr. Sezawa's theory, and from the characteristics of the resonance curves which we obtained, we can conclude that the eng ne should be located at the node of the ship's vibrat on according to the old and prevailing theory.

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