In general, the scantling calculation of stiffeners, in the light of ordinary simple beam theory, has been carried out after the following means : -
Max. field moment=C×W×l,
C being the coefficient which depends upon the fixing conditions of the ends; W the total load; and l the span.
The author, however, proves the way to the higher approximation by dint of allowing for the acting load, and is to propose the following new formula : -
Max. field moment=C× (1-ψ) w×l,
ψ being the load reduction factor due to the end constraints. And he is also to state the simple method to find out the value of C provided the conditions are taken for granted.

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Relations between ultimate tensile strength and elongation are examined for various shapes of test specimens.

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The Author ever stated that the torque fluctuation of the intermediate shaft must be considered when calculating the strength of propeller. The present paper explains the relation between torque fluctuation and bending moment at the root of blade of propeller by its own inertia.
The wave form of one complete period on film which recorded by Author's torsionmeter can be expressed as follows :
Δ-Δm=Σγn sin (nω0t+ψn),
where Δ=displacement of image from zero line (cm),
Δm=mean displacement of image from zero line (cm),
n=wave number of the component of harmonics included in one period,
ω0=2πN/60 for 2-cycle engine,
= πN/60 for 4-cycle engine,
N=revolutions of shaft per minute,
γn=amplitude of the component (cm),
ψn=phase angle of the component.
Assuming the positions of nodes of forced vibration to be the same as those of free vibrations, fathermore neglecting the inertia of shaft, the formula for amplitude of shaft at propeller position referred to any one of the mode of vibration is
θL=1/Ip2Σqγn sin (nω0t+ψn),
where.
L=virtual moment of inertia of propeller (g.cm2),
p/2π=natural frequency per second for the mode of vibration under consideration,
q=torque per unit displacement of image (dyne. cm-1).
Practically, it is enough for this purpose only to consider the vibration with one node.
The angular displacement, angular speed and angular acceleration of propeller are
φ=2πN/60t-1/Ip2Σqγn sin (nω0t+ψn),
ω=2πN/60-1/Ip2Σnω0qγn Cos (nω0t+ψn),
α=1/Ip2 Σ (nω0)2 qγn sin (nω0t+ψn).
Assuming that the distribution of virtual mass along the blade is similar to the distribution of actual mass of blade and the boss is sphere, the virtual moment of propeller and the bending moment at root of a blade are
I=zk'ρ1∫R0 RγAR2dR+ρ2π/60 (2Rγ) 5,
M=-α·k'ρ1 [∫R0RγAR2dR-Rγ∫R0RγARdR],
where
z=number of blades,
k'ρ1=virtual density of blade (g.cm-3),
ρ2=density of boss (g.cm-3),
2Rγ=dia. of boss,
2R0=dia of propeller,
A=sectional area of blade at a rad. R.
k' is larger than unity. M is the vector quantity whose direction coincides with axis of propeller shaft.
Assuming that the contour of blade is elliptic and sectional form of blade at any radius is parabolic, the above formulas can be simplified as follows

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This paper deals with the period of free rolling of ship theoretically and experimentally, and the following results are obtained.
(1) F (θ, θ), the resistance couple for the free rolling of a ship, which could be assumed as an arbitrary function of θ and θ, is expanded as follows.
F (θ, θ) = (I₀η) + (I₁₀θ±I₂₀θ²+I₃₀θ³) - (I₁θ·θ±I₂θ·θ²),
where θ is a transverse inclination of the ship, and I₀, I₁ I₂, I₁₀, I₂₀ and I₃₀ are the various coefficients which do not contain θ. It is well known that I₀, the coefficient of the first term, is an additional mass moment of inertia and the second terms are the frictional, eddy-making and wave-making resistances against the rotational motion of the ship. And it was found that the third terms indicate the mutual effect of the amount of the second order between the additional mass moment of inertia and the damping on each other, and it was proved experimentally that the effect of this terms on the damping is very small, but the effect on the additional mass moment of inertia comes to the great amount in the case of a ship with bilge keels, whereas this can be neglected as small in the case without bilge keels.
(2) T, the half period of the free rolling, is approximately expressed as follows.
T_??_π√ (I+I₀) H/WhG₃_??_T₀√H/G₃,
where
H=1+4θ/2θ_m (f₁θ₀+f₂θ₀²),
G₃=1+1/2k₁θ₀²+1/3k₂θ₀⁴,
W=weight of displacement,
h=metacentric height,
θ₀=initial amplitude,
θ_m=mean amplitude,
Δθ=decrease of amplitude within the range of one swing,
(I+I₀) =apparent mass moment of inertia for small θ₀,
T₀=free rolling period for small θ₀.
And G₃, a non-dimensional factor which is a function of the form of the statical stability curve, indicates the effect of the ship's form, and H, a non-dimensional factor which is deduced from the terms, proportional to θ·θ and θ·θ², indicates the effect of the damping on the virtual mass moment of inertia, where f₁ and f₂ are constants to be evaluated ty the experiments. And the correctness of this formula is proved by the experiments.
(3) By the experiment results it, was proved that in the case of a ship with bilge keels the coefficients f₁ and f₂ have the values of the considerable amounts, but without bilge keels those values are so small that, putting H_??_1. the period can be approximately calculated by the following simple formula.
T_??_T₀/√G₃.

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The Author examined the effect of the grouping arrangement of the barges upon their resistance at several depths of water.
Eleven kinds of arrangement were tested by three same models. The towing resistances, measured in each case, are shown in Fig. 4. From these results, the percentage increase of resistance due to variation of the arrangement, or change of the depth of water, are brought out.

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In the previous paper, the Authors dealt, with the open water tests on 4-bladed propellers of three series, namely, increasing pitch, constant pitch and decreasing pitch. The general plan of the propellers and the test results are represented in Fig. 1 and Fig. 2 respectively.
The present paper is an account of experiments, successively carried out at the Teisinsyô Ship Experiment Tank, with the same series of propellers working behind a rather fine singlerscrew cargo ship model fitted with an ordinary stream-lined rudder.
The ship model, the characteristics of which are shown in Fig. 3, was towed at a speed of about 2·0m/s throughout the tests, so as to keep the condition of flow constant; while the propellers were driven over possibly wide range of slip. The radial wake distribution measured by blade wheels is given in Fig. 5.
The test results presented in Fig. 6 were analysed depending upon the equivalent advance speed derived from the method of torque-constant identity. Fig. 8 gives the relative rotative efficiency for the usual range of slip plotted on the base of real slip.
Generally independent of the pitch ratio, the relative rotative efficiency decreased more and more slowly, as the slip increased. Accordingly, within the range of working slip, the relative rotative efficiency can be reckoned as constant for a narrow range of slip. It may therefore be suggested that the diameter giving the best propeller efficiency behind a ship of such type as represented by the model used is almost the same as, or a little greater than that in open water.
So far as the present experiments concerned, the increasing pitch propellers gave higher relative rotative efficiency than the constant pitch propellers did, and the decreasing pitch propellers the lower. But, those differences, especially at higher slip, were not remarkable.

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By open and behind experiments with a series of rudders, the experimental formulae for the normal pressure and centre of pressure were obtained.

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The present paper is the first report of the investigations to find out the law of comparison applicable to the model tests in shallow water, and gives a simple method of modifying Froude's law of comparison, with the results of preliminary experiments.

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The authors investigated the effects of the depth of water on the resistance of ships by the towing experiments for series models of C_p=0·60, varying the displacement-length ratio and the breadth-draught ratio in three classes respectively. The experimental results.were analysed as the percentage increases of residuary resistance for the V/√gD-values, where D is the depth of water, and it was found that the so-called critical speeds of the phenomena were given as a function of V/√gD. The results were shown in Figs. 6 to 8, by which the effective horse power for actual ships in any depth of water can be calculated when the results in deep water are known. The percentage variations of the speed effected by the depth of water were also plotted for each value of D/L, as were shown in Figs. 16 to 21. In spite of the curves of percentage increases of residuary resistance for the same displacement-length ratio and various breadth-draught ratio presented some difference between them, the curves of the speed variation coincided with approximately in the wide range of practical use.

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The authors, who made a general introduction on this subject in the last meeting, here explain the technical contents of the provisions of the Side Framing, Shell Plating and Pillars as a first touch.

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Boiler plant efficiencies of the Dry-Combustion Boilers at sea trials, on board the ships constructed by the Kobe Dockyards, Mitsubishi Heavy Industrial Co., are reported. The researches with respect to the feed water, boiler water, water treating reagent and scale formation of this type of boiler are informed. The construction, weight and cost of this type of boiler are compared with those of the usual Scotch boiler and the construction of the Mitsubishi Dry-Combustion Boiler is briefly explained.

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