By the measuring apparatus specially designed for the rudder resistance, as shown in Fig. 1, the resistances of the rudder plate, single plate rudder and reaction rudder, all shown in Fig. 2, were measured in both open water and propeller race. These results, presented in Fig. 12, show that the presence of the propeller increases the resistances of the rudder plate and single plate rudder, but decreases that of the reaction rudder to the extent of the negative resistance at the higher slip ratio.
By the propeller dynamometer the thrust and torque of the propeller, shown in Fig. 4, were measured in both open water and front of the rudder. These results, presented in Fig. 11, show that the presence of the rudder increases the thrust and efficiency of the propeller.
Analysing the results of the self-propulsion tests on the high speed single screw cargo ship model, shown in Fig. 13, with and without the rudders, the similar results were obtained.

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An experiment was made as regards the relation of the sectional area of the electrodes and the thickness of plates to arc welding current.
The results are as follows :
(1) The current increase or decrease is proportional to the sectional area of the electrodes.
(2) And the current varies practically by a (e^-bx₁-e^-bx₂) where x₁ and x₂ are the thickness of the welded plates, a and b constant.
From these two results, author has made a diagram which gives the suitable current in electric arc welding using any size of electrodes and plates.

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Diesel engines have doubtless great economical advantages, especially when used for marine propulsion, but at the same time entail some disadvantages; firstly, the uneven torque developed, secondly, the huge dimensions required for larger outputs, etc. These can be completely solved by interposing the Vulcan hydraulic coupling and gear. Moreover, introduction of the mechanical reduction gearing permits favorable propeller revolution, nd obtains a considerable gain in propeller efficiency.
The purpose of this paper is to discuss the following advantages of the double Vulcan geared Diesel engines installed in a proposed single screw cargo boat, compared with several direct propelling ones, Such as;-
a) Smooth running, b) Less machinery weight, c) Smaller machinery space, d) Lower running expenses, e) etc.

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There are several methods for the protection of the screw shaft from the corrosion in sea water. Even with the best methods of these, such as the continuous brass sleeve, we have met frequently with the trouble in making as well as after the services, especially in case of the long shaft.
For the sake of these defects we applled the vulcanized gum lining for the twin screw shafts of the new steamer S. S. Soya Maru, the ice breaking ferry of Imperial Government Railways. This paper is a report of the process of the vulcanized gum lining of that shaft at Yokohama Dock Yard. The paper notes also the other important advantages with this method, such as the weight saving and less expense. After some six months service the steamer docked and we found that the method was satisfactory with no defect in the result.

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In this Paper the author introduces the outline of existing conditions of pulverised coal burning ships with tabulated particulars according to his inspection through Europe and America, and also describes its apparatus, method of manoeuvering and several precautions on design and arrangement, mostly concerning the Clarke Chapman resolutor pulveriser, which was employed in the newly-built steamer “Johore Maru” and “Nagoya Maru” of the Ishihara Industrial and Transport Co. Ltd.

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The welfare of a nation depends upon its national power, which is surely the back ground of the politics, economics and militari tic strength of the nation. The promotion of the national power of Japan depends entirely on her industries. The fundamentals of industries are the natural resources and human power. Although the recent engineering development of Japan has been remarkable, the shortage of her natural resources has hindered the advance to the world's competitive market.
The independence of Manchukuo and the concert with Japan have given opportunity to render the latter substantial supplies of the former's abundant resources. Consequently, the old industrial policy of Japan should be reformed to meet the future advancement.
The industrial consolidation between Japan and Manchukuo is very natural, both having the same spiritual ideals of mutual assistance, which should promote the well-being of both nations with consequent augmentation of the peace and welfare of the Far East.
The failure of the League of Nations is entirely due to the lack of recognition of the outstanding features in the Far East and also of the industrial strength of Japan, which compelled her to withdraw from the League and caused the futile argument of an arms embargo.
The world's culture originated in Asia and proceeded toward the West, as the Sun goes. The material civilization was highly amplified in Europe, and propagated to America and lastly reached Japan. Now, the nation of Japan is responsible for the re-circulation of the material civilization, well-amalgamated with spiritual cultivation. On this ground, the industry of Japan should be the prime mover for the cultural advancement of the world. Under such consideration, the fundamental re-establishment of the Japanese industrial policy has also very great meaning for the well-doing of the human race.
Manchukuo and Japan differ in their geographical conditions and natural resources. Both countries have things which the other has not, so that industries of these two countries should be established upon their own merits, and the unification of these industries will promote the prosperity of both countries owing to natural nutual assistance. With this in view, Manchukuo should be in charge of heavy industries such as mining, iron and steel making etc., whilst Japan should take refined industries such as mechanical, electrical, shipbuilding, constructional engineering etc.
Some Japanese shipbuilders consider that Manchukuo is not a market for the shipbuilding industry, but the author considers that there is ample scope for the development of this industry in Manchukuo, in river transportation, shipping naval affairs. etc.
The idea of the Manchurian market would, however, mean only a minor economic circulation in this part of the Far East, so Japanese engineers should aim at the world's competitive market.
The shipbuilding industry having very keen relations with all other branches of industries such as steel making, mechanical, electrical, ordnance, civil, structural engineering etc., it is in the most suitable position to become negotiator amongst the various industries in order to establish the new national industrial policy of Japan, and to this great aim the shipbuilders should endeavour with their utmost energy as the pioneer for the reformation, which will not only promote the prosperity of Japan, but also is a substantial policy for the shipbuilding revivail and then toward the international competition.

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A cantilever wing, composed of two spars, ribs, a special rib, a box-rib at the wingroot, a stiff end rib and drag bracing, and covered with doped fabric, was load-tested for the purpose of determining the amount of contribution of these members to the stiffness of the wing.
The wing was attached to the testing tower in our Institute, and the deflections at eight points on the each spar were measured with dumpy levels set horizontally on the floor, and by reading the millimeter scales attached to the points. The wing was firstly tested in complete condition, then fabric was stripped off, the special rib was cut, the drag bracing was removed successively and lastly the normal ribs were cut. In each case, it was loaded with a single load on either front or rear spar at the point of attachment of the end rib, then it was loaded on both spars and adjusting the amount of loads the deflections of the two spars were made equal. By this method, the effects of the various members on the torsional stiffness of the wing, especially the binding effect of ribs and the effect of the doped fabric, were determined. The materials used in the spars were tested for tension and compression, and the fabric for shear by specially designed testing apparatuses, and the moduli concerning to these characteristics were obtained. The results of calculations using these figures and that of experiments were compared and discussed.

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This paper investigates dynamically under some simplifications the main features in the early stage of three-points-landing i.e. the falling motion from the flattened-out level flight (if any) and bouncing after the touch to the ground, considering the elastic force of the landing gears and the clamping forces due to inner friction of the gears as well as due to air resistance of the main plane. How the pilot's skill of landing manœuvre and the characteristics of the landing gears have influences on bouncing of the aeroplane is also examined, and further the shock load factor in landing is theoretically calculated and compared with that which is required by the Japanese Regulation for the Strength Calculation of a Civil Aeroplane.
Conclusions obtained, see Chapter VIII.

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This paper deals, mainly by experiment, with the apparent increase of moment of inertia in the rolling of ship, due to the surrounding water, and the following results are obtained.
For the ship with bilge keel, the ratio of the apparentincrease of moment of inertia toWB²/6 (where W and B are weight and breadth of ship respectively) is proportional to the square root of the amplitude of rolling, and inversely proportional to the cubic power of the period, and consequently the period of roll decreases as the amplitude falls down.
For the ship without bilge keel, that ratio is practically independent of the ampli tude, and is composed of two parts, the one being independent of the period and the other inversely proportional to the cubic power of the period.
The part that is inversely proportional to (period) ³ may be attributed to the eddy fluid motion produced by the projecting portion of the hull, i. e. the bilge keel or the keel part of the aft body, but the explanation can not be given. The constant part for the ship without bilge keel, is of the same order as the calculated results by assuming the water perfect (which calculation is given in the appendix), so this part may be due to the potential fluid motion around the smooth part of the hull, in which the midship and fore bodies of the ship are included.
In the present experiments, only the one model is used, so the effect of size (i. e. the scale effect) could not be studied.
In the appendix, the theoretical apparent increase due to ideal water is calculated by hydrodynamical method, the results being compared with the experiment.
The theoretical value for ship with b. k. is generally larger than the experimental one, but the values for ship without b. k. are very near.
Also the apparent increase of mass for the case of the V·shaped body imping into the water is calculated, which may be used in some calculation of the landing of seaplane on the water.

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In connection with the problem of stress distribution in a deep beam with one hole⁽¹⁾it is of interest to study also the more practical case where two circular holes are perforated for the purpose of the weight saving, etc. In this paper, the problem is considered as that of a deep beam having two circular holes, the depth of which is great enough compared with the size of holes. The solution is given for bipolar co-ordinates, for which the co-ordinate curves are co-axial circles.
Since the problem is considered as that of plane stress, the stresses can be expressed in terms of a single functionX, say stress function, as given in (3) in this particular coordinates.⁽²⁾ We assume this functionXto be (X₁+X₀) and suppose thatX₁gives no stresses at great distance from two holes and the stresses in terms ofX₀only satisfy the conditions at that point, though each function satisfies independently the linear partial differential equation of the same type as given in (4) or (5) in our particular co-ordinates.⁽²⁾ Two solutions are obtained, (1) for the case of a deep beam containing two circular holes of equal radii on each side of the neutral axis and (2) for the case of a deep beam containing two circular holes on the neutral axis.
The results of mathematical investigation may be summarised as follow;
For the case (I). In this case, thex-axis is the neutral axis and they-axis is the vertical axis, on which the centers of two holes lie. These two circular holes lie at equal distance on either side of the neutral axis. The stress function which satisfies the conditions above mentioned is given by (8). The stresses in beam are given in (9), (10), (11) and (12). The constants in (12) which are determined by the conditions on the periphery of holes (13), namely, (14) are given in (15). The stress distribution round each hole is as shown in Fig. 3 by plotting the values of stresses on the normals to the periphery of hole. The stress round each hole has two maximum values at the symmetrical points A and B on the vertical axis through centers of holes. These two maximum values are some multiples of the stresses at the corresponding points in a non-perforated beam. These multiples are 2.85 atAand 3.22 atBfor P/D= 3.75, Pbeing the center distance and Dthe dia. cf two holes. For larger values of P/D, these multiples are nearly constant as shown in Fig. 1. The stress distribution on the neutral axis and on the vertical axis through centers of holes are given in Fig. 4 by plotting the values of stresses on the normals to the neutral and vertical axis respectively.
For the case (2). In this case, the y-axis is the neutral axis of beam, on which two equal circular holes lie. The stress function for this case is given in (17) and the stresses in beam are given by (18), (19), (20) and (21). The constants in (21) are determined by the conditions round each circular hole (22), namely, (23) and are given in (24). The stress distribution round each circular hole in this case is not symmetry about the vertical axis through its center as shown in Fig. 5, since the existence of the another Hole on the same neutral axis has great influence upon the stress distribution in the neighbourhood of the other hole. But this effect due to the another hole will be decreased as the center distance of two holes is increased and, for larger value of P/D=10, the stress round of each hole may be approximately given by that for the case of a deep beam having one circular hole as shown in Fig. 2. The stress for the latter case is given by
ββ=MR/I (sin θ-sin 3θ)
M=uniform bending moment.
R=radius of circular hole.

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For the approximate calculation of the virtual mass of an airship we use in general that value of the “equivalent ellipsoid.”
In this paper, the author tries to calculate the virtual mass of an airship by the application of the theory on “the energy of a body moving in an infinite fluid” given by G. I. Taylor : that is, determining the source-sink and the doublet distribution for the airship model U-721 by Kármán's method, to calculate its longitudinal and transverse virtual mass respectively.
The results are compared with the values obtained from those of the pendulum experiments of the same model and a good coincidence is evident.

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As the approximate solution for the problem of a fan-shaped plate under uniform pressure, clamped at all boundaries the present writer proposes to the practical use the following expression for deflection of plate on strain energy method :-
deflection w=Cr² (r-a) ² (r-b) ² (1-cos2πθ/θ₀)
Where a and b are two radii, a>b, and θ₀ is an angle between two radii.
If put b=0, we have for a sector
w=Cr⁴ (r-a) ² (1-cos2πθ/θ₀)
which was published by G. Ei. in “Sulzer Technical Review” No. 4, 1931 page 17.

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As the problem of simple torsion in beam is analogous to that in the steady flow of potential, the stress functions are obtained theoretically in several forms for the same problem. In our case, not on curvilinear orthogonal co-ordinates but on polar ones, we have two modes of expression for stress function, one being obtainable from Laplace equation and the other from Poisson one according to boundary conditions.
As appendices short arguments on the problem of circular cylinder with varying rigidities, as well as numerical table of Bessel function of order ±1/2, ±3/2, ±5/2 and ±7/2 are given to the reference. Of course the latter is an “un-established one” subjected to further revision.

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Two pairs of seaplane floats are tested in the experimental tank. The plan view of bow waves have been photographed. Actual flow lines have been obtained by towing the models while the coat of white paint over the bottom surface of the floats still wet, thus streak traces being shown quite clearly. Water lines during the gliding can thus be ascertained. The hydrodynamic lift is deduced by substracting the computed hydrostatic buoyancy from the total force acting upward.
Water at the bow rises along the bottom surface forward to the head of the float and is then thrown sidewise. This bow sheet forms the undesired dirtiness, which often accounts for damaged propeller. The whole sheet around the floats takes the form of the butterfly wings, the roots of which are the crests of the bow wave.
Discontinuity, if any, in the curve of resistance appears to be the difference of water resistance and air resistance at the back of the step. As far as the symmetry and form of the flow lines at the bottom, little difference is found between single float and twin float arrangement.

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Impact bending tests were carried out on specimens of Spruce and Plywood between the range of temperatures from +66°C to -60°C. The testing machine used was an Amsler's 4 ton universal machine for testing wood. When this machine is used for impact bending, it is possible to measure the maximum pressure on the supports besides the energy required to break the test pieces, so that the equivalent modulus of rupture can also be computed.
Results show that both Spruce and Plywood change in their mechanical properties with variation of temperatures. Thus the absorbed energy shows a minimum between 6°C and -10°C, and the equivalent modulus of rupture increases almost linearly with decrease in temperature.
Moreover prolonged cooling produced no difference in the results as compared with those cooled for a short time. And it was observed that test pieces which were first cooled and then brought back to the normal temperature regained their initial properties.

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