In the Central Meteorological Observatory of Japan in Tokyo (φ35° 41' N, λ139° 46' E) the registration of direct solar radiation had been in the regular program of observations in the interval between January 1930 and April 1932. In the present report, the variation of the dust content of the atmosphere in the middle part of Tokyo is studied statistically using the method given by A. Ångström (Geografiska Annaler Bd. 12, s. 130, 1930). The maximum and minimum values of monthly means of the amount of dust content β were occurred in July and February respectively. As for the diurnal variation no conspicuous change was perceived, although in the morning of summer months the dust content were larger than those of the afternoon. In the morning of winter months, on the contrary, the values of β were smaller than those of afternoon. It is worth to be remarked that the dust content, in general, varies with the velocity and direction of wind, and the relation seems to be especially prominent in the case of northerly wind with velocity of more than 5m/sec.
It is a well established fact that when winds blow from the offing towards the coast or from the coast out to the offing a vertical circulation of water is produced, and it follows as a natural consequence that the depth of shallow seas or bays may change. In this paper, is treated this subject in case of bays of moderate size, in which the effect of tidal and oceanic currents etc. is small. In Part I a discussion is made on the movement of sand particles at the bottom of a bay. The method of treatment of the subject is dwelled on in Part II, where a provisory functional expression Φ (s) is introduced to represent the effect of prevailing winds on the depth of a bay, where s is the length along the coast line, and its application to an actual ease is shown in Part III. The result seems to justify this method.
As seen in Pl. 10, a mass of clay plastered on a wooden board was cracked with the gradual dehydration. On examining these, it is found:- I. A linear relation between thickness of the clay plaster and size of the block produced as the result of cracking. The author took the distance between two neighbouring eracks along the contour line of the plaster (the line of equal thickness) to represent the size of the block. II. Various forms of the cracks as to be classified as follows: 1. T-type. (Right-angled.) The most ordinary type. 2. H-type. Fig. 4. 3. L-type. Fig. 5. 4. ξ-type. Fig. 6 shows how the erack of this type grows. 5. Echelon cracks. Only seen on the surface of clay in its early stage of dehydration. (Fig. 7, left.) 6. Three-ray type. (a) Fig. 8, a (b) Fig. 8, b. Three-ray cracks making angle of 120 degrees with each other were absent in the present experiments.