There are many surveys of cities in the world on the regularity known as C. Clark's model of urban population densities indicating that population density varies with distance from the center of the city according to the equation D_x=D₀e^-bx where D_x is the population density at distance x from the center. D₀ is the density at the center, e is the base of the natural logarithms, and b is a natural logarithm measuring the rate of change of density with distance. However, the survey of Japanese cities are rather few, hence applicability of this model was tested for fifteen Japanese cities, selected from the cities with population of more than 100, 000 located in the central part of Japan. Those are Tokyo, Ôsaka, Nagoya, Kyoto, Yokohama, Shizuoka, Wakayama, Gifu, Sakai, Utsunomiya, Chiba, Kofu, Toyohashi, Nara and Hachioji.
The data used in this survey are those for 1965 based on the grid square comprising nearly one square kilometre made by Bureau of Statistics, Office of the Prime Minister.
The principal facts observed in this survey are as follows.
(1) This regularity is applicable for all of this cities except for Yokohama and Sakai those which are included in the contiguous urban built-up area of Tokyo and Osaka respectively.
(2) The value of the density gradient, “b”, is highly associated with the population size of DID of the city, that is, it reduces according to the size of DID population. However, it seems to be affected duely by landforms surrounding the city.
(3) Clark's model has better fitness in case of daytime population than in case of resident population in Tokyo.
(4) Large variations of the values of “b” due to difference of directions from the center of the city are found not only in Tokyo but also in Ôsaka.
From these observations it can be concluded that Clark's model is applicable for principal cities of Japan, and that other generalizations regarding this model which have been observed in other countries such as USA and UK may be drawn in Japan.

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Recently environment pollution, such as air pollution, water pollution, noise and so on has frequently occurred in Japan in accordance with rapid growth of national economy and its main sources are factories which produce pollution materials.
About 13% of factories of Japan are concentrated in Tôkyô in 1970. One of characteristics of manufacturing industry in the city is that the ratio of small-scale factories is larger than national average. These small-scale factories often locate in residential district or commercial one. The possibility and scale of pollution are large in the districts where such type of land use exist.
Fig. 3 shows the relation between population density and sulphur excretion density. This Figure makes it clear that dangerous and uncomfortable districts where both population and sulphur excretion show high density are distributed in the eastern and northern parts of Tokyo.
Factory removal is one of the means to promote areal differentiation of land use and to reconstruct urban structure. It was practised in Tôkyô, too, but the actual effect by this means is not yet enough, mainly because the scale of the undertaking is small compared with the scale of the agglomeration of manufacturing industry in the city.

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In recent years, the wood price has been remarkably gone up because of an excessive demand and a scanty supply of the national wood resource. Under this condition, the pulp industry which depends on the national wood resource, has achieved some changes in the pulp timber, namely the changes in kinds of wood. They involve not only the changes in quantity and form of the raw materials, but also changes in the pulp timber supply area.
In this paper, the author attempted to analyse how some changes in the raw materials of pulp industy in Tôhoku District affected the wood-chip industry which was related to the pulp industry.
The results are summarized as follows:
1) Although the timber cost has occupied a high percentage in the pulp product price and has been remarkably going up in recent years, the product price has been maintained because of the structure of the pulp industry. For this reason, it is necessary to improve the supply of material for the pulp industry.
2) Improvement of the supply of raw materials is a change in kinds of pulp timber, such as a change from the conifer timber to the broad-leave timber as well as utilizing the wood-chip for the purpose of using the timber more inexpensively.
3) The distance between the pulp factory and the wood-chip factory has been reduced in order to reduce the transprot cost which is eventually contained in the pulp timber cost. This tendency is particularly remarkable in the Tôhoku District where many pulp factories have been recently established. And the distribution of the related wood-chip factories was contracted.
4) Many large specialzied factories which are different from former small combined factories, have been established by changing the pulp timber from conifer timber to broad leave timber, and these factories are in subcontract under the pulp factories. New relation thein the financial and the capital relations, have arisen between the pulp factories and woodchip factories.
5) Increase in the import of pulp timber is recently remarkable in Japan. The conifer timber is mainly imported in Tôhoku District where is a huge broad leave timber resoruces. Therefore we can find no large change in the wood-chip industry in Tôhoku District except partial adjustment of the production and the location of the factories near ports.

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Air temperature observations were made mainly along the national road, Route 4 in the southern part of Miyagi Prefecture, on cloudless, calm days in 1969, 1970 and 1971, using a car with a Thermister-Thermometer. The results of analysis of the data can be summarized as follows:
1) Warmer areas, like ‘heat islands’, were observed in most of the settlements regardless of the city size.
2) Differences between the air temperatures at the centers of settlements and those outside of them have been estimated between 0.2 and 1.1°C.
3) Local climatic fluctuations caused by the above-mentioned settlements have thus been taken away and new distribution of air temperatures from Sendai City to Shiroishi City has been obtained along the national road, Route 4. This result may be applied to other cases or other regions.

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The purpose of the present study is to obtain basic infomations on the relations between the air-borne pollen and the living vegetation surrounding the air-borne pollen collector.
Ten stations were selected to collect air-borne pollen (Figure 2).
The air-borne pollen which were caught on one square centimeter of a slide glass smeared with petrolatum-oil was observed from 13 March to 4 August, 1971. The slide was set at a point at each station, kept out of the rain, and replaced by new one each week.
The results are given in Figures 3 and 4. Pollen detected through all stations amount to one family and 36 genera of tree pollen and 10 families and 6 genera of herbaceous pollen and a spore. About 97per cent of the total pollen detected in this study was dispersed in the atmosphere during period from middle March to early June. Planted trees (Cryptomeria and Pinus) occupied over 87per cent except stations 1, 2 and 3.
Fagus was found in small quantities (1-2%) at stations 6, 7, 8, 9 and 10 in spite of the absence of the living beech. This pollen was derived by the wind from montane zone dominated by F. crenata being about 40km from these stations.
Abies, Tsuga and Betula were detected 6-16 grains through all stations. These trees are scarcely found in the area studied, although found in the subalpine zone of Mt. Zaô. Abies, Tsuga and Betula were probably carried by the wind for a long distance (about 40-60km).

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On some navigational charts, there are numerous large submarine sand ridges to be seen where strong tidal currents occur. Such ridges in northern and eastern Yellow Sea and Malacca Strait are described here, and the distribution pattern as well as some general features are discussed.
Evidently, sand ridges have been formed by the agency of tidal flow, by which process, sedimentary ridges and ridges of erosional remnant are formed. The ridges of straight type are distinguished, too, from the ones of snaky type by the distribution pattern. The straight ridges are generally very large and long, and are parallel each other with regular intervals.
The distribution of straight ridges is limited within 54 meters in depth and disappears in the region where ancient sediments crop out as relic or where tidal motion is weak. Regional difference in the depth of ridges reflects the forming age of ridges. Lower ridges are older ones constructed when sea level stood at 20 meters in depth about 7, 000 years ago. They have been modified and annexed to recent ridges, and evolved into present form during the following sea level rise.
Generally speaking, ridges of locally or regionally equal depth have equal interval in distribution, and in good correlation, the deeper the depth of ridges, the wider the interval. This connection is suggestively analogous to the relation between bottom height and depth of flood flow.

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In this paper, the writer shows the urban growth of Muroran and the neighbouring two cities, and analyzes some factors and effects of the urban growth. The results obtained are as follows:
1) Built-up area was developed over the Etomo Peninsula till the end of World War II. After the war its expansion has been seen in the eastern part (Rantô district) of Muroran.
2) Urban growth extents to the two neighbouring cities, Noboribetsu and Date, since 1965.
3) There are three main factors in urban growth of Muroran; the first is the enlargement of manufacturing industries, the second is the construction of public residences and the third is the fear of industrial pollution in the central part of the city.
4) According to the urban growth, the center of population distribution moved from the western part to the eastern part of Muroran, and according to the change some urban facilities have been moved to the east, so that the Ranto district seems to become a new C. B. D. in Muroran before long.

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1. Hanawa Mine produces Kurokô, the black ores. The mine has been regularly operated since 1936. Judging from the history of mining and the scale of operation, it is typical of the mines which are operated on a medium scale in Japan.
2. This mine is located in a remote place. The mining places is in Akita Prefecture and its dressing plant in Iwate Prefecture.
3. Most of the workers at the mine live in the houses provided by the company in the districts of Onnadaira and Senosawa. So those who come to work from neighborhood are few.
In recent years, there has been remarkable tendency that workers decrease in number and advanced in age.
4. In Senosawa district there are mining facilities in a group. The construction factories are well equipped in regard to blacksmith, machine-repairing, iron-working and so on.
As the institutions for the people living in this district, there are various facilities for administration, medical treatment, welfare, education, culture, business, recreation and other public services.
5. The expolitation of this mine has influenced Aziro and Hanawa Towns and especially Tayama District.

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J. C. Hudson's diffusion model of an innovation is very interesting one in its relation to a combination of central place theory and diffusion theory. The result of a single application of this model to the establishment of bowling centers in Kantô district is shown in Fig. 1. According to this figure, this sort of diffusion model may be a useful vehicle for geographical research.

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