This paper describes the thermal conductivity of steel determined by the following processes :
(a) To investigate the diffusivity, specific weight and specific heat of steel and determine thermal conductivity of steel with above results.
(b) To determine the thermal conductivity of steel by a apparatus devised by the authors
The value for the thermal conductivity of steel at about 100°C. is concluded to be 0.158 cal./cm.°C. sec. The thermal conductivity at temperatures between 20° and 400°C. is also determined.

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When a ship rolls among irregular waves, the effective coefficient of resistance which is given in the form
α_c=α+4/3β/T_cθ₀
varies according to the relative angle θ₀ and the period 2T_c of the resultant rolling composed of free and forced motions. Hence the component free and forced rollings have variable amplitudes in each swing, different from those when they take place independently of each other. Taking account of this fact there was proposed a new method of calculating the so-called criterion amplitude, in which the coefficients of resistance α and β were assumed to be constant. For four actual ships the criterion amplitudes were calculated for various values of period ratio T_s/T_w and compared with those obtained by Mr. R. E. Froude, showing about 10 per cent. difference for ships of moderate resistance.
Next the practical maximum amplitude θ_fmax which a single wave can give to a ship after an increasing swing was calculated for particular resistance to rolling, assuming the ship to be initially rolling in her natural period to the same amplitude as that of the forced rolling due to the wave under consideration. It was found that for a ship of moderate resistance the value of θ_fmax is nearly expressed by the sum of the forced angle and the free angle after one swing in cases where T_w/T_s is less than 0.8 and greater than 1.2, and that the value θ_fmax divided by the maximum effective wave slope becomes greatest when T_w/T_s is a little greater than unity according to the degree of resistance.

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To study the properties of the rolling motion of ships, especially through large angles, ship-models are usually employed ; consequently a law of comparison must be in existence between them. By Mr. W. Froude's assumptions on the frictional and eddy making resistances and on the waves created by the rolling of ships it has hitherto been believed that the coefficients of extinction are constant for similar ships at corresponding periods. But it was found from experiments that these coefficients are different by a large amount between actual ships and their small models, and by a moderate amount between similar ship-models. Particular experiments were therefore carried out to study the nature of resistances to the rolling of ships. For the investigations on the frictional and eddy making resistances three cylinders of different diameters and a cylinder fitted with fins of various depths were suspended vertically in water sufficiently deep and caused to oscillate in various periods. As to the wave making resistance waves created by the rolling of similar ship-models were carefully measured. These experiments showed that the frictional resistance to oscillation was expressed by the sum of resistances proportional to the angular velocity and its square, the coefficients being different in each period for each cylinder ; that the eddy making resistance was expressed by the sum of resistances proportional to from first to third power of the angular velocity. the coefficients being also different in each period for each depth of fins ; and that the height of the created wave did not vary as the amplitude of roll, but varied as the breadth of the ship-model. Based upon these results a new law of comparison was established and its validity was shown after having been applied between an actual ship and her model, and also between three similar ship-models.

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The principle of this torsion-meter is same to that of torsional strain-meter for intermediate shaft invented by the Author. By this torsion-meter we can read easily amount of torsion of shaft at any angular position, so find out the mean torque.

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As the turning properties of ships are usually discussed only from the experiences and impressions of those who handle ships, the author analysed the problem by experimental investigations, and found the principle that, within a limit of the angular velocity of usual ships in turning, where the turning resistance is proportional to the square of the angular velocity, the turning angle from rest to a point where the angular velocity becomes constant is 1 radian, if a ship is turned about its axis by constant turning moment. Therefore, the turning moment of a ship is equal to the sum of the kinetic energy of the ship due to its mass and moment of resistance of ship-form due to the water mass.
With ship-models and a ship the following experimental investigations were conducted : -
1. The points where the angular velocity and speed of the ship become constant after putting the helm over to some angle.
2. The point where the angular velocity of the ship becomes zero after the helm in turning is put back to zero.
3. Turning angles where the angular velocity in turning becomes zero and then constant, after the helm is put over to sone angle in the reverse direction.

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The authors propose a new-type experimental tank with a cylindrical cross-section for the towing experiment of submerged bodies. Their attempt at this tank is to minimize the effect of the wave-making phenomenon on the free surface of the water which is liable to occur in towing the submerged body at an usual depth of immersion, or to avoid inaccurate resistance measurement due to the augmentation of idle resistance experienced by very long swords suspending the model immersed so deep as to make its wave formation practically null. Some results of experiments carried out in a very small tank of this type are given together with the project of a large tank, 3.0 meters in diameter.

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The paper begins with an account of the recent welcome tendency of decreasing. ship disasters, year after year, owing to the result of advance of ships' life saving appliances; and then proceeds to examine how many sorts of boat davits and their accessories have been proposed, invented, or tried in the latest twenty five years together with some suggestions as to how minute and cautious consideration should be paid to the boat davit design in future, giving some instances of actual ship disasters.

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The possible causes of vibration damping in a ship were previously considered, with a result that the formation of surface waves and structural inner damping including the damping force due to movements of loads on board the ship take the important part. From the present investigation it has been ascertained that if the damping resistance be structural, the concentration of that resistance in such a position that the deformation in elastic vibration is large, is efficient, for which purpose the material inner damping in fibres remote from the neutral surface or axis shall be increased as possible. As to the distribution of the resistance lengthwise the ship, the two-nodal flexural vibration and the one-nodal torsional vibration can be damped by the concentration of the damping resistance near the midship section. In the actual ship, although the cargo serves as a kind of structural damping, the last condition is not always fulfilled. At all events, the concentration of damping resistance in certain special parts of the ship for reducing her vibration, shows a satisfactory condition that is far beyond the one resulting from the concentration of elastic resistance in similar parts for strengthening the same ship. Finally, if the damping resistance be due to wave formation, the two-nodal flexural vibration can be damped by wide midship section and the one-nodal torsional vibration by the flat vertical surfaces toward both ends.

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Fatigue tests were carried out and the so-called “Goodman diagrams” were obtained on two sorts of structural rolled steel plate. The effects of machining, welding or riveting of these plates were also observed, and it was shown that the weld metal on the surface was decidedly detrimental to the fatigue strength of the plate.
By X-ray diffraction method it was also observed that the fundamental difference exists between the mechanisms of fatigue cracks and tensile fractures, and the method is suitable for practical application for judging the causes of failures of structural parts.

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The authors explained the ultimate strength of riveted plates, and compared it with practical calculations.

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