It has been well admitted in oceanographical surveys that a reading of the wire-gauge does not always indicate the true depth of a sounding layer because of inclination of the sounding wire caused by ocean currents and winds. In order to correct errors resulted from the slope of the wire the writer has made an attempt to estimate curving patterns of the sounding wire under water and to draw the correcting curves, using data on the falling velocity of a messenger, which was obtained by Watanabe (1943), on the basis of the equation of motion of a naturally falling body.
It is hoped that this attempt would be of help for drawing some more correcting curves with better accuracy.

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This is a continuation of my papers under the same title, and a method is given to solve the equation for mass transport on a rotating globe, W. H. Munk and Henry Stommel have been kind enough to suggest me that the annual mean wind system over the North Pacific are zonal. Stommel also pointed out that the value. of horizontal mixing coefficient I used in my previous papers, was too large, and I carried out the computation anew, taking these advices into account. I made some additional improvements, considering the entire Pacific Ocean on a rotating globe. Numerical solutions have been worked out one for a zonal with system and another for an anti-cyclonic wind system, assuming the coefficient of lateral mixing to be of the order of 10⁷ c. g. s. The mass transport for the Kuroshio was found to be 80×10¹²g/sec and 4410¹²g/sec for, zonal and anitcyclonic wind system respectively, actual value 65×10¹²g/sec determined from observations lying between these limits.

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The currents and the accumulation produced by winds in the water consisting of two layers of different densities are investigated on the assump-tion that the eddy viscosity is negligible along the boundary of two water masses. The computed profile of the boundary surface is in good agreement with observation.

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It is known that Cl ion in sea water diminishes the phospho-molybdenum blue on the phosphate determination by ATKINS∋method, so the correction must be made on the value obtained. These correction factors are varied by the authors from 1.00 to 1.35. This variation shows that there might be some other substances which disturb the colorimetry. It has already been pointed out by some investigators that these substances are colloidal iron, cupper and colloidal parts of mud. Some experiments were made on this problem, and it was found that nitrite in the water, too, diminishes the phosphomolybdenum blue and disturbs the determination.
It is often observed that the phosphate content of the water added with preservatives increases in the time of storage since bottled to analysis. Phosphomonoesterase, which liberates ortho-phosphate from organic phospho-rous compounds, is detected in the sea water and plankton tow water. The action of that enzymes in the water containing plankton or other organisms, is suggested one of the reasons of this phenomenon.

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During the months from March, 1950 to June, 1952, observations of colour of the sea, transparency, and plankton volume were performed in the “Extra” area, which is a circle of 50 sm radius, the centre being at 39°N, 153°E. The monthly mean values of these elements have been computed. Values of the plankton volume used here have been calculated from the settling volume of plankton which were sampled from 100 m depth to surface with Kitahara's net (Hensen type, bolting silk XX13, diameter of with mouth: 22.5 cm). The annual variation in colour of the sea and transparency shows nearly the same characteristies as previously reported by the present author (1951); the maximal values are observed in spring and autumn, while the minimal ones in summer and winter. As to the seasonal variation in plankton volume, a conspicuous maximum, so-called a phenomenon of burst growth, appears in spring and a less marked maximum in autumn, and a marked minimum is observed in winter, and also, in a less degree, in summer. An experimental formula D=21.8 V-0.2s, where D represents transparency in meter and V plankton volume in cc/m3, has been determined, although somewhat unsatis-factory conditions are involved; for instance, disregard of composition of plank-ton, inequality between the value of transparency and the depth of net haul, etc. Functional relation between colour of the sea (F) and transparency, and also between plankton volume and colour of the sea has not be determined, since irregular straggling of the points on the F-D and the V-F diagrams does not permit any curves to be drawn. However, it has been found that correlation coefficients between them are -0.7 and 0.4 resnectivelv

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