The temperature change of freely falling water drops has been theoretically studied by A. C. Best, Gilbert D. Kinzer and Ross Gunn in the process of growing and evaporating of a water drop in cloud physics. The concrete studies on this problem has been required from the practical standpoint such as cooling of water for industry and rising of water temperature for irrigation for production of rice crop in Japan by making the water drops. The theoretical studies in the past referred to the very small water drops and the temperature in a water drop being assumed to be uniform, only the thermal exchange between a water drop and its ambient air was considered. But we must consider the temperature distribution in a water drop of large size for putting water drops to the practical uses such as in agriculture and industry. Now the author considers the temperature change of freely falling water drops by taking account of the temperature distribution in a water drop and compare with the theory in the past and the results of experimental works of Gilbert D. Kinzer and Ross Gunn.

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It is very difficult to measure the velocity of ground water and other very low velocity of a flow such as in a reservoir, sea or lake. The author presented a new method of measurement in Report I, which is summarized as follows.
(1) The current meter is portable for the field use.
(2) The direction of flow can be also determined.
(3) The velocity in the hole (Fig. 1) is twice as large as that of the outer region.
(4) The flow direction in the hole is parallel to that of the outer region.
In this method, the most serious factor which affects the accuracy of measurement is the horizontal diffusion of warmed water mass in the horizontal pipe of the current meter. In order to take off the above undesirable effect, following relations are shown.
(a) In the case of U> U_T:
in the outer region: U=L /T, in the hole: U=L/2T
(b) In the case of U< UT:
in the outer region: U=L/the case of U=U_T:
in the outer region: U=L/2 (1/T₄+1/T₃)-L/T₁, in the hole: U=L/4 (1/T₃+1/T₄)-L/2T₁ where
U: very low velocity of water
U_T: velocity of diffusion of warmed water mass in the pipe, (see Fig. 2)
L: length between H and S (see Fig. 2)
T: time for the warmed water mass flow from H to S (see Fig. 2)
T₁: T₂: T₃: T₄: time for the warmed water mass flow from H to S (see Fig. 3).

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In this paper, the characters and the problems on applicable ranges and parameters have been discussed of log-normal distributions of the Slade-type having the three parameters as follows:
F(X)=1/√π∫^ε-_∞e^-ε2dε
Case I ξ=αlogx+b/x₀+b-b<x<∞
Case II ξ=αlogg-x₀/g-x -∞< x< g
CaseIII ξ=αloggx/x₀g-x₀/g-x 0<x<g
in which a, xo and b or g are constants. From the results of analysis, it was disclosed that the parameters b or g corresponding to lower or upper limits have no physical meanings, and the applicable ranges and parameters are shown as follows.
Case I, b<0: the curve B in Fig. 1 and the curve B₁, in Fig. 2. b=O: the curve B in Fig. 1 and the curve B_o in Fig. 2. b>0: the curve B₂ in Fig. 1 and the curve B₂ in Fig. 2.
Case II: the curve G in Fig. 1
Case III: the. curve B2 in Fig. 2.
Moreover, it was pointed out that the case I is superior to the other cases in adaptability for hydrologic data.

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Abstract A practical solution of the extreme value (largest value) distribution known as the most rational distribution formula for frequency analysis of the annual maximum hydrologic amount has been proposed in this paper. Practically, there are two types in this distribution as follows;
F (x) =exp (-e^-ξ)
ξ=α(x-x₀): Gumbel Distribution
ξ=αlogx+b/x₀+b: Type A of Log-extreme Value Distribution
in which α, x_o, and b are constants.
The solutions by moment of this distribution were already proposed by Gumbel and the author, but the results by those methods were not so good in fitness to hydrologic data. In hydrologic statistics, in order to avoid such a fault, there is a trend to notice an expedient method using the concept of plotting position.
In this paper, the concept of plotting value proposed by the author has been used. Now, the plotting value y is the linear reduced variate of actual variate x, and it is determined to minimize the estimation error of parameter. In this paper, the character, in which the sample moments of plotting value y are corresponding to those of actual variate x, has been utilized.
The method of practical analysis has been shown as the function of sample size n, and some practical tables and diagrams have been prepared. The usefullness of this proposed method were recognized by applying to the actual data of precipitation in many observatories in Japan.

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There are often phenomena in which very large or very small values are contained in hydrologic data. In estimating the distribution function of hydrologic amount, the decision of adoption or rejection of such data, which should be named as the singular value, is one of the most important and fundamental problems in hydrologic statistics. Moreover, the forecast of such singular value is also a very important problem.
There are, however, hitherto no studies on the criteria for adoption or rejection and forecast of such singular values.
In this paper, first, the relation has been established between the probable singular value and its probability, applying the concept of two-sample theory on normal sample. Next, the criterion for adoption or rejection of a singular value has been proposed using the concept of the binomial distribution, and some practical tables have been prepared.

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This paper presents the analyses of rain simulator infiltrometer experiments to make clear the functional relation between the intensity of rainfall and that of infiltration of the ground surface with a certain structure of soil and covering.
For this purpose, it is necessary that, first of all, the presence of a certain functional relation between them corresponding to a settled structure of the ground surface should be detected and hence the variation of the ground surface should be discussed.
In these experiments to detect the above-mentioned functional relation, a rain simulator discharging the waterdrops of very small sizes, the impact energies of which are practically negligible, was used.
Through analyses of these results, it is confirmed that the intensity of infiltration of settled ground surface with a certain structure of soil and covering has, at a certain period, the characteristic relations respectively in the three ranges of the intensity of rainfall, as follows:(1) γ≤γ_o...i=γ
(2) γ_o≤γ≤γ_u...i=f (γ)
(3) γ_u≤γ...i=i_max,
where
γ: Intensity of rainfall
i: Intensity of infiltration
γ_o: Minimum intensity of rainfall for surface runoff occurrence
γ_u: Minimum intensity of rainfall for attaining the upper limit of intensity of infiltration (i_max).
It is elucidated that the intensity of infiltration in the range (2) of rainfall is approximated with a sufficient accuracy by the following linear expression:
i=αγ-1-(1-α) γ_o, where a is a coefficient.
These analyses actually show that α and γ_o are equal to 0.340 and 63.3 mm/h respectively, and their correlation is very satisfactory.
It can be practically concluded as a result of the experiments that this ground surface is composed of two parts having appreciable different capacities of infiltration, which are almost repre-sented respectively by ro and ru as the intensity of infiltration of them. Furthermore, this result is very useful for dealing rationally with practical problems of runoff phenomena, i.e. the estimation of excess rainfall, etc.

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From an observation of phenomena occurred in a dry soil-layer on the surface of a Kanto-loam field, I found out some characteristic relations between forming of this layer and a vertical distribution of soil-moisture in the lower layer.
The main points of these relations are as follows;
1. After the soil-moisture of the layer lower than 5cm depth reaches 28 volume-percent, its receding speed reduces.
2. On the contrary, under the same condition, the decrease of the soil-moisture in the upper layer becomes very conspicuous.
3. As the dry soil-layer is formed, the evaporation from the soil-surface is performed as if the soil-moisture were stripped off from the upper layer.
4. Under these conditions, the soil-moisture in the lower layer (from 5cm to 20cm depth) is nearly constant at every stage of change.
From these results, it seems to me that the lento-cappillary point plays an important role in forming the dry soil-layer, and that it is necessary to research the physical properties of this characteristic point.

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In a previous paper (I) on rheology of bentonite paste, it was experimentally shown (on the electrically dialysed bentonite) that the concentration φ_o in the state of sedimentation is a critical point of flow; under this concentration bentonite paste behaves as Newtonian liquid, and above φ_o the paste behaves as Bingham body.
The rheological properties of soil paste was investigated mainly on high concentration instead of low concentration in the previous paper. Samples used in this experiment are as follows:
T₁: clay (yellowish brown), montmorillonite, tertiary.
T₂: clay (gray), montmorillonite, tertiary.
Va: clay (brown), allophane-hydrated hallysite, volcanic ash (diluvial).
From the results we summerized as follows:
(1) A critical point from Newtonian liquid to Bingham body is also verified in soils.
(2) In high concentration, the yield value appeared markedly, i.e. the soil paste behaves as Bingham body. The lower the concentration of soil paste is, the smaller the yield value. Plotting yield values (θ) against the concentration (φ), we may write an empirical equation
1+θ=exp (a (φ-φ₀)) where a=numerical constant.
Yield value of Ca-soil is smaller than that of Na-soil at the same concentration. These phenomena are systematically explained as follows. As Na-soil solvates to a larger amount than Ca-soil or H-soil, effective concentration (φ*) is higher than that of Ca-soil or H-soil.
(3) Further we have studied the change of sedimentation volume of soil on which Ca or Na ion was added. In the state of sedimentation, concentration (φ) of Ca-soil is greater than that of Na-soil.
(4) Na-soil behaves in flow as if a suspension, which is higher in concentration than unsolvated state.
(5) Thixotropy flow is remarkable on Na-soil in high concentration (φ>φ₀) In volcanic ash soil no difference in flow appeared among Na, Ca and H added soil.

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The authors have continued a series of the experimental studies in order to make clear the mechanism of the percolation control of water by using Bentonite.
In the previous report, the mechanism of the percolation control of water caused by the percolation-flow of Bentonite in the soil was clarified. The purpose of this paper is to consider the case in which the percolation-flow of Bentonite does not take place. On the condition that the particle size is definite, it is the problem how the total swelling volume comprising the substantial volume and the swelling water volume acts on the percolation control, or how the percolation control is made in the process of swelling.
For this purpose some comparative experiments by using Talc which is not so swelling as Bentonite was performed in the following two case:
(A) Percolation under the air-dried condition in the two samples; one mixed with Bentonite in the soil and the other mixed with Talc so as to make their total volume equal.
(B) Percolation of the same samples as (A) filled up in the percolation apparatus under saturating condition.
In these cases the effect caused by the swelling pressure appeared only in the case of (A) and that of kneading only in (B), and the control effects on the original soil were about 40% in the total swelling volume, about 30% in the swelling pressure and 67% in the kneading effect.(Generally the percolation control of (B) was more effective than (A) in the case of clayey soil).
Consequently, it was concluded that on such a condition as imposed in this paper, the mechanism of the percolation control of Bentonite is mainly due to its total swelling volume and swelling pressure.

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The analysis of the sedimentation in the river mouth is very difficult due to complex connection with wave characteristics, drift size, river flow and other factors. However, it is a Most important ploblem for the river mouth improvement.
The authors carried out experimental studies on the profile and dimensions of the sedimentation in the mouth of a model river having an immovable bed with model sand beaches possessing median diameters of 0.56mm and 0.176mm respectively. These equipments were set up it a wave channel 0.5m wide and 18 m long located at Kochi University, and the experiments were made under various conditions of wave and flow of the river.
As the results of these researches, maximum height (h_smax), entry length (l_s) and quantity (Q_s) of the sedimentation in the river are expressed, depending on the relations between tractive force of wave and critical tractive force of sand, and between the discharge of wave and the river flow.
They are given by the following equations:
_??_
These equations show that the sedimentation increases according as the nondimensional value of the tractive force (H₀/T√sgD) and that of the discharge (2πITQ_w/H₀L₀) decreases.
These are applicable to the actual beaches where the drift diameter is large, and will give effective data for the river mouth improvement.

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The writer reported previously about influence of temperature on the dynamic modulus of elasticity of concrete.
In this report are presented the relation between static modulus of elasticity and temperature of concrete, and the influence of temperature on dynamic modulus of elasticity and logarithmic decrement of concrete with different age and moisture content. The following conclusions may be derived from the experimental results:
1. Static modulus of elasticity varies with temperature in such a way that it decreases step by step with rise of temperature.
2. Dynamic modulus of elasticity of concrete increases with age and with duration in which it is kept moist.
3. If the concrete is kept dry, the decrease of dynamic modulus of elasticity with rise of temperature is larger than when the concrete is kept moist.
4. Logarithmic decrement of concrete decreases with age and dryness.
5. Logarithmic decrement of concrete increases with rise of temperature.

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