It is quite in recent years that the Japanese shipping has made marked progress.
About thirty years ago it was still in a state of infancy, the tonnage owned by Japan being far inferior to that of other shipping nations.
But now Japan stands third as regards tonnage next to the British Empire and the United States. This is chiefly due to the fact that the two wars Japan had with China and Russia awoke both the government and the people to the imminent need of promoting the development of her shipping industry, which was further urged by the Great War. Thus the Japanese shipping made so rapid a progress that Japan soon cut a conspicuous figure in the world shipping.
Now such development of her shipping was attended with the growth and development of her shipbuilding industry. After the Great War on account of the very severe depression felt in Japan, as in other countries, her shipbuilding industry faced a most difficult situation, it is true, her new tonnage being greatly reduced ; but in 1919-20 Japan rose to the third position in this line of industry.
As for the skill and workmanship I can confidently sly that Japan can well stand comparison with any of the senior nations of Europe and America, and any vessels, however big, may be made by Japanese builders, if the financial conditions here permit. More especially as regards building of warships, Japanese builders have shown superiority of their own which is solely original.
Further it must be noted that the development of shipbuilding industry affects in no small measure other industries, as it involves so many lines cf work that the greater part of the cost is outside the control of the industry, being covered by many other industries concerned.
Although it is a happy fact that such auxiliary industries have so far advanced that they are now in a stage where we have not to look to foreign countries for any material or equipment, as we used to do, yet in view of there being still much left to be desired, I do hope further dovelopment in such industries as well.
Finally one thing more I would like to add is the classification of ships which has very close connection with shipbuilding. In Japan the Teikoku Kaiji Kyokai is the only national classification society recognized by the Government. By making an alliance with the British Corporation, American Bureau and Registro Italiano, the society commenced classification business in 1920 and pushing the work to the best of their ability they have now on their Book vessels of 800, 000 tons.

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Using curvilinear orthogonal co-ordinates, the auther investigates the stresses in a plate having (1) a hypotrocoidal hole, especially one resembling a rectangular hole with rounded corners, (2) circular holes arranged on a straight line with an uniform pitch. The results are applied to deck-openings, cargo-ports, rivet-holes etc. The mathematical treatement is given in the appendix.

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This paper being supplementary to the previous one (referred to the VOLLUME XL), deals with the characteristic curves of Diesel engines obtained from the land trials.
For the marine engines it is more rational to treat with the fundamental characteristic equation as P_i=P_o + βP_b than to do with it as I.H.P.=F.H.P._o+γB.H.P., for the values of M.I.P. (P_i=F.H.P._o/C_oN + γP_b) derived from the latter equation increases as the load descends within a certain range of load and P_i = ∞ when P_b or N= 0, which is evidently contrary to the fact. But out of the certain range of load the latter equation holds good. approximately and deserves of practical use.
For the so-called constant speed engines, both characteristic equations will bring almost the same result, for in this case assuming N to be nearly constant or to decrease linearly as the load increases, then the derived equation P_i=F.H.P._o/(C_oN) + γP_b from the equation I.H.P.=F.H.P._o+γB.H.P. will be reduced approximately to a form P_i =P_o + βP_b where P_o_??_ F.H.P._o/(C_oN) and γ_??_β. But to speak exactly, N increasing to a degree parabolically as the load decreases, then the corrected equation will be I.H.P.=F.H.P_o + (β +K/n × max. B.H.P.^(1-n)/n) B.H.P. at any revolution.Y, assuming that the equation P_i= P_o + βP_b holds good for the truly constant speed engine. Next assuming P_o to increase with the increase of speed and basing on the above assumption, the characteristic equations for marine engines will be P_i = P_o+ φ₁P_b^1/2 + φ₂P_b and also I.H.P.=ψ₁N + ψ₂N² + ψ₃N³.
The values of M.I.P. will be somewhat affected by the constant deviation of revolution from the propeller law speed or the normal constant speed under mean constant torque. Some engine has the tendency to indicate a little higher M.I.P. in High Speed Series than in Low Speed Series and in some case vice versa. Another engine indicates the almost constant values of under mean constant torque. So it is not easy to obtain the definite conclusion as to the effect of deviation of revolution upon the values of M.I.P. under mean constant torque.
The fuel characteristic equation can be treated most generally as a form of F= aH.P.³ + bH.P.² + cH.P. + F_o, where F_o is an assumed initial fuel consumption per unit time. The specific fuel consumption equation f = aH.P.² + bH.P. + c + F_o/H.P. indicates the concave or convex curve according to the positive or negative values of F_o. Within a certain load F is larger in High Speed Series than in Low Speed Series for the same values of H.P., but beyond that load vice versa.
The characteristic equations obtained from the land trial records at various series of speed will be very useful to determine more approximately the corresponding B.H.P only from the measured values of M.I.P. and N after the engine installed on board ship, specially in case of propeller speed not according with the propeller law speed due to the effect of propeller immersion or ship's draught etc.

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In this method fine charcoal powder made from hemp reed is fed into air the flow of which is to be studied. At the inlet a small ignition tube is fitted through which the powder being kindled is passed into the current of air. Thus the flow of air is made visible to the eye or sensible to photographic plates.

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Simple and accurate rules similar to that of Tchebycheff. A numerical example is given for a sine curve and the result compared with those by Gauss', Tchebycheff's, Simpson's and Trapezoidal rules.

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The purpose of this paper is to place on record certain launching particulars of Myoko, a cruiser of 10, 000 tons standard displacement. In addition of ordinary launching calculations, thorough investigations were made for stresses to be experienced on various parts of the ship during launching, and the estimated results were compared with the records obtained by strain recorders. The difference of position of lift by stern actually observed with various methods and estimated position was investigated. The distribution of pressure on the fore poppet, and the water resistance upon the ship during launching were investigated.

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During 1926-1927 the time-study was carried out to ascertain the time-rate and the piece-rate which have been used since 1905 in Kure Naval Dock Yard.
The study was classified as follows, “Determinate, ” “Indeterminate, ” “Long time” and “Short time.” Firstly the indeterminate and long time method was studied and then determinate and short time next.
As the results, one of examples of riveting, Table No. 12 shows their difference being about 10% and so considerable.

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In this paper are described some particulars in connection with torsiographic measuäements of torsional vibration in Diesel engine units. From torsiograms taken; the characteristic features of torsional vibration of each order can be clearly seen. Numbers of the orders, which have bcen observed by the author in his experiments, arc as follows:
a) For 4 cycle 6 cylinder engine....3^rd, 4^th, 4.5^th, 6^th, 7.5^th, 9^th, and 12^th.
b) For 4 cycle 10 cylinder engine....4^th, 5^th, 7. 5^th, and 10^th.
c) For 2 cycle 6 cylinder engine....4^th, and 6^th.
Of the above orders, the 3^rd, 5^th, and 6^th have been found the most severe vibration and their ranges are also exceedingly wide. According to the author's estimation, the range of the 3^rd order critical vibration is over 200 revolutions, that of the 5^th and 6^th orders are from 40 to 80 revolutions. Judging from the results obtained, it will be seen that the range diminishes as the number of natural vibration per minute becomes less.
The torsional stress due.to the heaviest torsional vibration is roughly estimated 10 times as much as the mean torsional stress at full load.
Lastly some suggestions are made to overcome the difficulties caused by torsional vibration, i.e. firstly by creating turning moment ay the free end of vibration, for instance, by adopting fly wheel embodying 'slipping device; secondly by altering the-elastic iondition of the shafting at or near the nodal point, for instance, by adopting proper type of friction coupling; and thirdld by shifting suddenly the whole range of vibration, for instance, by adopting electro-magnetieally controlled fly wheel.

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Thin flexible narrow strips of paper are attached to the upper surface of a model wing for the purpose of preventing the back flow of the air along it at a large angle of incidence.
Thus furnished wing is called the feathered wing.
The experiments were made on the four sorts of model wings, namely; low-cambered thin wing, medium-cambered thin wing, medium thick wing, and thick wing.
The general results obtained so far are that the feather serves to increase the lift and the stalling angle of incidence of the wing in appreciable amount. The phenomena are most marked for the low-cambered thin wing.

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The auther investigated theoretically the relation between the size of the stabilizer and the amplitude of rolling in several cases;
1. When the ship is forced to roll by the stabilizer, Δθ_n=2Θ-a (θ_n+Θ) -b (θ_n+Θ) ²denoting the couple produced by the stabilizer by WmΘ and the maximum attainable amplitude is given by 2Θ-a (θ_n+Θ) -b (θ_n+Θ) ²=0
2. When the rolling is quenched by the stabilizer in the still water, -Δθ_n=2Θ+a (θ_n-Θ) +b (θ_n-Θ) ²
3. Rolling amongst regular waves. In the case of synchronism, the maximum amplitude is reduced by the stabilizer to θ given by the equation 2Θ+a (θ_n-Θ) +b (θ_n-Θ) ²-φπ/2=0 provided Θ≤φπ/4. If the size of the stabilizer is so chosen as Θ=φπ/4, the maximum amplitude is only φπ/4. The larger the size, the less the amplitude, but a vibratory rolling occurs in some cases owing to the too large power of the stabilizer.
The theory is compared with the model experiment made by Dr. Motora, showing a fair coincidence.

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