In the Yamamoto's feed-pump engine, the main valve chest and the auxiliary valve chest are made independent, so as to reduce the length of the main valve and the difference of expansion, and the space for the movement of the main valve was able to be uniformly distributed. The test results of 72 sets of feed-pumps with this system for high-pressure boilers of 200600 lbs./sq. in. are as follows : -
1. The piston speed was uniform and the engine performance was smooth.
2. The shock, vibration and sound were reduced.
3. The efficiency of pumps was improved and the steam consumption was reduced.
4. It enabled to make starting and stopping of the engine easier and simplified the overhaul inspection.
In this paper, the author precisely describes the improved points of this pump in comparison with the Weir's type, yet he says that these are not of absolute nature.

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Regretting that there is no suitable method of estimating the concentration of acid, the author devised the simplest apparatus, to which he applied the principle that concentration is determined by titration with standard sodium bicarbonate solution, using potassium ferrocyanide as indicator in presence of ferric salts.
The author next determined the suitable concentration of acid in which pickling can be completed in 1517 hours.

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The author explained N. M. Bronze and compared it to ordinary manganese bronze with high and moderate manganese content in regard to the main qualities required for marine propellers, namely,
1. Resistance to corrosion and erosion by sea water,
2. Tensile strength etc., and homogeneity of material,
3. Casting and machining properties,
4. Cost,
5. Suitability for repair by welding, fairing, etc.,
all based on the results of tests actually carried out on propeller castings and gave a conclusion as to the general superiority of N. M. Bronze over the others.

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The water-lines of cargo ship forms, regarding as the straight lines at bow, midship and stern parts and the free stream-lines connecting these, are determined by the Schwarz-Christoffel method of conformal transformation for the both cases of the limited and unlimited widths of water. Comparing the distributions of pressure and velocity of water along these water-lines, the effect of the side-walls of an experiment tank upon the resistance of a model towed in it is discussed two-dimensionally, with some experiment results.

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The largest Marine Diesel engine ever built in Japan was made by Messrs Mitsui Bussan Kaisha at Tama Yard and tested with succesful result. The engine is to be delivered to Messrs. Kokusai Kisen Kaisha. The engine is of Mitsui B & W's type, fitted with direct coupled supercharging blowers, of the latest supercharging system and capable to develop 6, 000 B.H.P. at 115 r.p.m. for normal full load and proved to develop 6, 900 B. H. P. for over load, which is an epochmaking figures in the world for a single acting Diesel engine. In this paper the characteristic construction of the engine and the principle of the new system of supercharging is described and some are also picked from those of bed tetsts.

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This is a supplemental and conclusive paper to the previous one in Journal of “Zosen Kiokai” (Soc. N. A. Japan) Vol. XLII, and deals with the mean indicated pressures in a cycle and in a whole engine, characteristics in land and sea trials, a certain aspect on the Admiralty constant and finally the methods of working out the equivalent B. H. P. at sea.

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In the first section of this paper, the author describes several practical methods of minimizing the deformation caused by the application of arc welding on the hull construction, such as symmetrizing method, constraining method, water-cooling method, multiple beads method, heat-absorving method, and pre-straining method. And then, he explains the general matters on the carbon contents and the diameter of electrodes, the form of welding, the amount of electric current, and the speed of welding, to be taken care to minimize the deformation.

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1. Aluminium light alloys are all very weak for sea water corrosion. Even Duralumin, the best rolling alloy, and Silumin, one of the best casting ones, are not good on this point. Some alloys are really non-corrodible but not used due to their inferior mechanical properties and difficulties in casting, rolling or forging A new alloy was invented in our laboratory 6 years ago, industrial researches were completed and the products are now used in some works. It was named “Chlumin” as it contains chromium, but a few per cent of magnesium and iron are also added. A brief description will be given of it in the following pages.
2. Non-corrodibility. Castings of Chlumin and of an alloy of composition Cu 8%, Al 92 %, the most common one, both made by metallic mould, were immersed in 5 NaCl solution. Photo. I shows the result after 4 years. Chlumin gave only little deposit retaining even some luster, while, the other was severely corroded precipitating considerable mass of aluminium hydroxide. The machined surfaces of Chlumin and Silumin plates were exposed to air being sprayed by salt water every day. Photo. 2 shows the result after 2 months. Many black spots appeared on Silumin but Chlumin remained bright. This difference was observed also on specimens immersed in sea water for a year. Experiments were next carried out somewhat quantitatively. Specimens were immersed in 5% NaCl solution in separate bottles. The quantity of deposit and the weight decrease of specimen were measured after 40 days. The results are summarized in Fig 1. Chlumin was a little better even than aluminium. Silumin, Y-alloy, Duralumin and all others containing Cu or Zn were attacked severely. The variations of mechanical properties due to corrosions are shown in Fig. 2. Many test pieces of wire were immersed in 5 % NaCl solution and the solution was renewed at times to expose them to air for a day to accelerate the corrosion. Chlumin and aluminium wires, annealed or not, lose scarcely their strength by 5 months' immersion. The elongation decreases in some cases. While, Duralumin, variously heat-treated or not, loses both qualities rapidly. After 3 months the strength reduces to 80 to 20% of the original value and the elongation to 50 to 20%.
3. As a casting alloy. The mechanical properties of a cast alloy depend much on casting conditions. Fig. 3 shows the data on ingots made similarly using same metallic mould. Silumin was in perfectly “modified” condition. Chlumin is a little inferior to Y-alloy in strength and yield point but is superior to it in elongation and impact resistance. It is better than Silumin in every respect and is more easy to cast and safe to use as no special process (modification) is wanted on manufacturing. Any complex form can be cast resisting to severe water pressure test. Pistons of internal combustion engine and parts of electric motor have been used for more than a year with better result than Y-alloy.
4. As a rolling alloy. Wires of Chlumin are compared with those of pure aluminium and Duralumin in Fig. 4, being annealed at various temperatures. Duralumin aged after quenching from 510°C into water is exeedingly good indeed when annealed at temperatures below 200°, but becomes worse than Chlumin at 300°. Besides, it may not be a safe process of manufacturing to quench an alloy of melting point of 620° from above 500°. It may be very dificult to heat a large article uniformly above 500°. A little over heating will set in local melting, and when the temperature is too low some parts must meet the worst heat-treatment of Fig. 4. Heating on welding will spoil the good properties given by quenching and aging and it is often impossible in practice to quench, the article again.

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Making use of the results obtained by the measurement of pressure distribution over a rolling aerofoil in the wind tunnel, investigations were undertaken relating to the mechanism of autorotation at various angles of incidence and the justice of assumptions underlying the calculation based on the strip theory. Two quite different types of autorotation were discriminated by the condition of flow over the upper surface of rotating monoplane wing. Comparing the results of experiment and calculation, concerning the rolling moment due to each element of the wing, marked differences were recognised, especially at large angle of incidence. The causes of discrepancies were explained and the limit of applicability of calculating method was determined. Finally the importance of the relative position of the wing and the rolling axis was indicated as a cause of autorotation at large angle of incidence with large rolling speed, which corresponds to the “flat spin” of a monoplane.

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In this paper, the author intends to describe how the “Kotaka” (a little river gun boat) was lifted by a crane and put on board a ship when she was transported from the Tama Dock Yard, Japan, to Shanghai.
The hull of the boat is not so strong since she ha s very light scantlings, but she displaces 60 tons at the normal condition and her weight lifted was such amount as 53.5 tons. Therefore, it is a rare case to do such a work, and there were troubles to be overcome.
You will be interested in the author's explanation about the following items : -
The outline of the subject.
The general feature of the “Kotaka”
The calculation for the lifting arrangement.
The result of the work. etc.

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It is a well known fact that the rudder turns more smoothly and more efficiently in accordance with the turns of the screw spindle of the gear, if the difference of the distances travelled by the nuts is smaller.
After several investigations the writer found that the simplest and most effective process is to give an angle to the arms of cross-head when the gear is of such a simple mechanism.
The writer explains the process to determine the suitable angle to be given to the arms of cro s-head in order to lessen the difference of the travelling distances of the nuts.

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This paper deas, in the introduction, with the problem of wages of labourers which is the most important element of shop management, but insists on that a person well qualified for the post is also most important. It deals, in, the main discourse, with several kinds of premium systems, namely Rawan's system, Halsey's system and others. On the conclusion, it introduces a formula of a new premium system which is more effective. It deals also with the value of labour, the value of working and the efficiency of labour and working. As an appendix, the calculation table of labourages and premiums by the new system is shown.

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