Considering the effects due to mean stress and due to variable stress on the fatigue failure of ductile materials separately, the shear strain energy law (v. Mises-Hencky's law) has been applied to the fatigue test results for bending and twisting. The conclusion is obtained that, if the range of variable shear strain energy has a smaller value than a certain constant value, and if the maximum shear strain energy during one cycle of stresses does not exceed the shear strain energy corresponding to the statical yield point, a ductile material can sustain an infinite number of cycles of combined stresses, with neither fatigue failure nor statical yielding. In the light of this conclusion, a method, which gives the allowable stress for ductile materials under combined alternating stresses, has been derived.

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The accuracy of shaft horse power measured by torsion-meter depends upon those of both modulus of rigidity of shaft measured at land and torsional strain measured at sea. As the method of measuring the latter were already given by the Author in the Journal of Soc. N. A. Japan, No. 52, published on 1933, he intends to explain in this paper the accurate method of measuring the former and give the measured results on the modulus of rigidities of the intermediate shafts of thirty six merchant ships.

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The “Kinjosan Maru” is the first ship equipped with Howden Johnson improved Scotch boiler and Gotaverken turbo-compressor. The propelling machineries consist of two sets of boilers designed for working pressure 16 kg/cm²and steam temperature 315°C, and one set of triple expansion surface condensing reciprocating steam engine specially designed to suit Gotaverken turbo-compressor and superheated steam. The engine develops a normal output of 1950 I.H.P. at 82 r.p.m.
The trials were carried out at a light loaded condition and the results were quite satisfactory. The maximum speed of 14-5075 Knots was recorded at 89·75 r.p.m. and 2, 324 I.H.P. and the coal consumption trial shows reasonable results and the mean consumption was 0.445 kg/I.H.P.-Hr.

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The first part of the paper deals with the combination comprising a triple expansion engine, with poppet valves for high and intermediate pressure cylinders, and direct coupled to the main shaft line, and an exhaust steam turbine, to utilize the energy contained in the exhaust steam from the engine, double reduction geared to the main shaft line. In this system, the turbine is to work for ahead direction only; an automatic friction clutch is to disengage the turbine when the main engine is to run in astern direction.
Mechanical regilient coupling composed of friction disks and a number of coil springs is contained inside the first reduction gear wheel, and is arranged to take off uneven torsional shocks taking place due to the action of the crank shaft of the reciprocating engine.
In the second part, description is given about the combination consisting of a set of double compound high speed engine, single reduction geared to the main shaft line, and a low pressure turbine, double reduction geared to the same line. In this case an astern turbine is also arranged. The exhaust steam from the engine is controlled with special manoeuvering valve to enter into either ahead or astern turbine as desired and the valve is to cooperate with the reversing mechanism of the reciprocating engine.
Particulars of the ships having these systems of combination machinery are given in the attached table also the performance data of their maiden voyages are given in another table.
A sketch of the design of the machinery space of twin screw engines and its brief description is given in the last part of the paper.

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Since in the case of a ship the surrounding water is seemingly so deformable that the dissipation of vibrational energy of that ship in the form of radiating waves is hardly possible, the reason why ship vibrations shall actually be damped not slightly, is as a matter of fact difficult.
There are at least four possible causes of damping in ship vibrations, namely, (1) the water friction, (2) generation of pressure waves, (3) generation of surface waves, and (4) the structural damping force. Air damping is obviously out of consideration.
The solution of the problem was obtained mathematically for the case of flexural vibrations under an unbalanced force, its result being compared with reliable experimental data, so as to determine what kind of force is the most plausible one for the damping of the ship vibrations.
In the case of a ship of shallow draught the generation of surface waves is the primary cause, whereas in the case of a ship with full load and deep draught the effective structural damping resistance becomes the cause under consideration.
The details of the problem as well as its theoretical treatment will be described in Appendix towards the end of this paper.

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The antarctic whaling tanker, “Nisshin Maru” (22, 000 tons deadweight) was successfully built on 28 th Sept. '36 by the Kawasaki Dockyard Co., Ltd., Kobe, in the record of only 216 days from laying down of the keel to the delivery to Messrs. Taiyohogei Kabushiki Kaisha.
The vessel is the largest tanker of its kind ever built in Japan, and the following dates indicate the extraordinary speedy program at which she was built in such a short period.
The contract signed 28 th, November, 1935.
The keel laid 26 th, February, 1936.
The launching 1 st, August, 1936.
The official trials 14 th, September, 1936.
The Delivery 28 th, September, 1936.
There were many difficulties which they had to overcome, such as : difficult construction on an ordinary building slip not well arranged with up-to-date crane equipments, unusual short time limit of construction, and hardship of prompt collection of materials, etc.
They laid down therefore a strict schedule so as not to delay the delivery and by good luck, it was faithfully obeyed by the men of all departments of the Dockyard Co.
Combined with the mutual co-operation of all men and proper supply of all necessary materials, the schedule was very satisfactorily carried out in good order.
On the other hand, special attention wa so pa to the working hours as well as labour shifts so that the workmen should not be overworked either mentally or physically.
Thus their earnest efforts have at last produced good results with such an epoch-making record of speedy ship building which has never been experienced in the world.
In addition, this vessel adopted the “Isherwood Bracketless system, ” the simplicity of which has proved a good effect upon such a quick work as “Nisshin Maru.”
The principal dimensions are as follows :
Length over all…550'-0''
Length between perpendiculars…535'-0''
Breadth moulded…74'-0''
Depth moulded to upper deck…48'-9''
Load draught…34'-25/16''
Gross tonnage…16, 764 tons
Deadweight…22, 000 tons
Maximum speed…14'5 knots

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In our last paper, we treated the case in which the rectangular plate was supported or fixed at its boundary. Here we try to solve the question where the four edges of the plate are elastically clamped so that the plate is deformed to an intermediate form between those of supported edges and fixed edges, and it seems, it may give further practical formulæ embodying the case much nearer to the actual condition of the structure.
The general idea of the treatment is to assume the deformed surface of the plate may be represented as a superposition of two terms corresponding to those in the case of edges supported and edges fixed. The respective coefficient c₁ and c₂ of these two terms are taken so as to satisfy the condition c₁+c₂=1, so that the case “fixed edges” will be represented when c₁=0, and that of “supported edges” when c₂=0. A. simple method of obtaining the approximate values of c₁ and c₂ as above stated is considered in case of the rectangular plate with peripherical beams, and also with additional plates or stiffeners which are further conjoined to the above beams.
By expanding the above treatment, it was tried to obtain the practical formulae giving the amount of deflection of plates in question under uniform lateral pressure; buckling load and also the lowest frequency of natural vibration of the plates.
Those formula suggested in our last paper are, in fact, special cases of these now obtained in this transaction.

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Experimental results on the collapse of thin spherical shell under external pressure due to the elastic instability has not yet been published, so far as the author is aware.
In this paper, he intends to describe the result of an extended experiment with steel models of various sizes carried out at the Naval Technical Research Department, Tokyo, with a view to obtaining the data for investigation of this line. Since the measured values of the collapsing pressure in our experiment all fall short of those calculated with Dr, R. Zoelly's formula, a new idea of dealing with this problem is developed in the later part of this paper.

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