To study the effects of the forms of the frame-lines and water-lines of intermediate liner forms upon the resistance, approximately unaltering the coefficients of fineness and the longitudinal position of the centre of buoyancy, eighteen models are tested at Tei-shinsho Experiment Tank, and the results obtained are compared.

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We have constructed a small experimental tank in our factory for the model towing experiment of the seaplane floats and flying boat hulls. The tank is 60^m long, 2^m wide and 1.5^m deep. Maximum towing speed is 7.0m/s which corresponds the get-away speed of 80 to 100km/h, (43 to 54^kn) for the 1/10 to 1/16 scale models. Driving motors are coupled directly on the fore and rear wheel axles; each motor develops 10 HP. For the speed control Leonard's set is employed. The motor generater set is installed in a room at the end of the tank. The car is built from duralumin sh ets and angles and weighs with all fittings about 1.6^ton. The main brake is consisted of bronze jaws which are fitted on the car and loaded by the tension spring. Besides the rail of the truck another set of rail is fitted on which the jaws slide. Thus the friction between the rails and jaws brakes the truck. At the end of the tank there is a pair of “Oleo” shock absorbers which has a horizonatal stroke of 1 meter.

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This paper consists of two parts written under the following subjects.
1. Standard of the Strength of Floor Girders.
2. Spacing of Transverse Strength Bulkheads or of Compound Floor Girders.
Now the writer begs to explain briefly the meaning of some terms used in this paper in order to avoid miscomprehension or confusion.
Floor Girder: A girder consisting of a solid floor plate, main and reverse frames, and shell plate in the case of single bottoms, and a girder consisting of similar member stogether with tank top plate in the case of double bottoms.
Longitudinal Bottom Girder:
(a) Single Bottom.
A girder consisting of keelson plate, keelson and keel angles, foundation and rider plates, and flat plate keel in the case of centre line bottom girder, and a girder consisting of similar members on the side of the centre line of ships in the case of side bottom girder.
(b) Double Bottom.
A girder consisting of centre girder plate, top and bottom angles, centre line tank top plate, and flat plate keel in the case of centre line bottom girder, and a girder consisting of similar members on the side of the centre line of ships in the case of side bottom girder.
Compound Floor Girder-A compound girder consisting of two. or three of the floor girders fitted on consecutive frames and connected between the longitudinal bottom girders by an additional short keelson or side girder. The writer's idea of fitting girders of this kind is to specially reinforce the bottom of ships in lieu of a transverse strength bulkhead, and therefore these girders should be used in association with side frames and beams of the lowest deck specially reinforced, together with suitable number of rivets in gusset connection.

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We have had hard experience of many troubles for torsional vibrations in the shafting of Diesel ship; and as a result of available experiments in recent years, the progress of research works in this section is so great, that we can now calculate the critical speeds for torsional vibrations and manage the problems in the design. But having very little knowledge about the damping factors in the vibrations, we can not solve the questions perfectly by mathematics, and have nothing but for experiments to determine the amplitude and the range of oscillations.
In this paper, the method of calculating the critical speeds of shafting is described in detail, so that meanings and natures of torsional vibration can be easily comprehended. Then the evil effects and the remedies for this vibration are noted to call attensions, for the sake of engineers concerning in ship building.

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Dividing the distribution of circulation around the aerofoil into the transverse and longitudinal distributions, the lift on the rectangular aerofoil, the aerofoil with raked tips and the aerofoil with cut out have been obtained. And the theoretical values have been confirmed by the experimental results of the rectangular aerofoil and the aerofoil with positive raked tips.

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This paper gives Compression and Impact tests data on Mahogany for use in aircraft propellers relative to the effect of low temperature.
The tests were carried out from ordinary room temperature to -50°C by using liquid air.
As the result, in general the properties of mahogany at low temperature increase its rigidity and brittleness, especially from 0°C to -15°C. The compressive values increased gradually with decreasing temperature, and impact values decreased rapidly to about 1/2 of the ordinary room temperature at 0°C and continued to -15°C, but under -15°C the value increased again. It seems that the effect of freezing of moisture included in its structures, for no variations were found on the specimens of moisture off by drying 5 hours at 100°C.

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