A large number of investigations have been theoretically and observationally given on the problems of urban heat island. Some of them have intended to obtain the informations about the heat island of small towns (Tamiya, 1968 etc.) and that around a large shopping center. It is expected that the results from these studies 'on small towns or the like could be applicable to the explanation of the heat island of large cities. Judging from these studies, the heat island of small towns is thought to be formed under the condition of clear calm night with strong surface inversion. Most of the studies were, however, based on a few observations. The aim of this paper is to clarify meteorological conditions by which the heat island of small town is formed, based on forty examples of observations at about five hours after sunset by automobile with thermistor thermometer carried out from July 1978 to February 1979. Then the mechanism of the phenomenonn is examined.
Observations
Three small towns are selected for the observation in. Tsukuba Academic New Town. They are Ohzone, Takezono and Namiki with population of 1, 800, 2, 000 and 3, 500, respectively, in 1978. Ohzone is a small rural settlement which has been existed before the construction of Tsukuba Academic New Town, and consists of mostly one or two storied wooden houses. The latter two have been constructed for officials of the New Town and consist of multi-storied concrete block buildings. These three are located on a flat upland with a heigh of 25-30m a, s. 1. near the Higashi-Oodori Boulevard (Fig. 1).
Observation points and the route are shown in Fig. 1. Most of the points outside the small towns are surrounded by field, green zone and vacancy. Observations were started from the point 15 and ended at the same point running through 1-7-Ohzone-12-25Takezono-28-32-Namiki-34-35.
It took about 30 minutes to finish each observation. Therefore, time correction was not applied. The date of the temperature observations are given on Table 1.
Duplicate observations were carried out at the points outside the towns. Two observed values must differ because of the difference of the lane and time during the traverses. Discrimination among them is, however, difficult in practice. Means of the differences between two values and their standard deviations are given in Fig. 2, which shows that the mean values at all the points are smaller than 0.4°C, and that no systematic differences are identified.
Meteorological data representing the surrounding air conditions are acquired from the Environmental Research Center (ERC) of the University of Tsukuba (Fig. 1). The values of elements used for analysis are also given on Table 1.
Some features of the heat island
A case of distinct heat island is shown in Fig. 3 (Oct. 16. 1978). In this night, under the condition of clear and weak wind (1. 2 m/s, NW) the inversion reached 6.0°C in the bottom 28.5m layer. On the contrary, in case of indistinct heat island (Oct. 29. 1978, Fig. 4) the sky was covered with cloud and the precipitation of 20mm was recorded during the day. In spite of weak wind (1.0 m/s) inversion intensity was only 0.9°C in the same bottom layer.
Temperature deviation at each point from the mean temperature of the route is calculated for every observations. The average values of 40 observations are also indicated with standard deviations (Fig. 5). Northern part of the route is colder. The coldest is the point 6. Mean values of Ohzone, Takezono and Namiki are 1°C (Northern side) -0.5°C (Southern side), 1°C and 0.5°C, respectively.
For the further examinations, heat island intensity is defined here as the difference between mean temperature of the points inside the small town and that of specified points outside (for Ohzone, points 3-6 and 14-19; for Takezono, points 14-19 and 29-31; for Namiki, points 29-31, 34 and 35).

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Since D. L. Huff proposed a probabilistic trade area delimitation model for the delimitation of a trade area (the Huff model), a number of attempts applying the extentions of the Huff model have been devised to analyze competitive market behavior. These models are generally called the Huff type model or the multiplicative competitive interaction (M. C. I.) model. The theoretical basis of these models relies to a large extent on the Luce choice axiom. It assumes the one-to-one correspondence between choice ratio which is the probability of a consumer in an area shopping at a certain store and relative utility which is the utility ratio. of a certain store to an aggregate utility of all stores which the consumer can patronage. However, there is no proof of the existence of one-to-one correspondence. Therefore, the Huff' and Hufftype models which rely on the Luce choice axiom do not have the evident store choice mechanism.
The purpose of this study is to build an alternative probabilistic model which is strictly defined in terms of consumer behavior, and to compare this model with the Huff and Huff-type models.
Main charateristics of this new model are as follows:
Let X_i be consumers' utility on the ith store in a given district. As the utility X_i is not the same to all consumers in the district, we assume that randam variable X_i is normally distributed with mean μ_i and variance σ_i². Furthermore, we assume that the probability choosing a certain store is equal to the probability that a certain sore's utility is greater than the . other stores' utility.
In case of three stores (denoted 1, 2, 3), the probability that store 1 would be chosen (P₁) may be stated as follows
_??_
here f_i(x_i) is the probability density function of X_i, the function Z_i=(X_i-μ_i)/σ_i is normally distributed with mean zero and variance one, and K_j=(X₁-μ_j)/σ_j.
The following results were obtained applying this model to the data about Matsuyama city.
1) Assuming that the consumers evaluations of store attraction is normally distributed and that the choice ratio in which consumers choose a certain store is equal to the probability that the evaluationn of the store is greater than those of the other stores, the author was able to build an alternative probabilistic model which has more clear choice mechanism than the usual ones.
2) The proposed model, as the probabilistic model satisfies the necessary conditions,
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3) The R. M. S. error obtained from the Huff-type model is 9.5% and that obtained from the Huff model is 15.86%. In terms of fitness the former is about 6% better than the latter. This difference is considered to be caused by applying both models to close-by stores which have different selling space. Accordingly, if the Huff model is applied to this situation, it is expected that stores having greater selling space have larger expect ed values than observed ones.
4) As the R. M. S. error obtained from the proposed model is 10.5%, there is no significant difference in terms of the goodness of fit between the proposed model and the Huff-type model. Furthermore, both models have similar distributions of predicted values.
5) Therefore, the proposed model has the same performance as the Huff-type model, and at the same time it has more clear store choice mechanism than the usual probabilistic models.

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The purposes of his ar idle are o inves iga e he changes in geographical dis ribu ion of the impor -expor_??_ firms during the last one hundred years, and to relate these changes to the process of development of the central business district (CBD) in Kobe.
During the period from 1868 to 1899 the residential quarter for foreigners, which later became a foreign trade district, had been divided into 126 lots delineated on the basis of the European-style planning.
Trading firms, financial and insurance businesses, information and transportation services, and a self-governing institution, were closely located each other, and they formed special business district isolated from the main built-up area of Kobe city. Therefore, Kobe city had had two core areas specialized in administration and retail trade in the west and in wholesale and import-export business in the east until World War II (Fig. 1). In 1919, 70% of the import-export firms located in the former foreigners' quarter were owned by aliens. Thereafter, a mixed land use district with factories, import-export firms and workers' housing were developed on the east of the foreigners' quarter. A trade business district with a large number of import-export firms, financial and insurance businesses, and transportation facilities was formed on the west of the quarter (Fig. 2). The locations of import-export firms at the time of 1936 were on the southern side of the National Railway line extending from the Kobe station to the Shin-Ikuta River, where a number of tall buildings had been built; and this district almost coincides with the boundary of the CBD in 1970 delineated by Komori, et al. (1970) (Fig. 3).
In 1977, import-export firms extended to the east and north compared with their distribution before the War. The CBD delineated by Komori et al. (1979) also showed its extention to the east and north. Therefore, it can be said that the location of import-export firms has played an important role in the formation of the CBD (Fig. 4).
After World War II, the western core has gradully declined in consequence of the fact that the administrative organizations such as City Hall had moved to the former foreigners' quarter. The factor that changed the structure of Kobe city from two-cored to one-cored city, was the large-scaled redevelopment program of the CBD carried out, to a large extent, by the governmental investiment.
Chronological changes in total floor space of banks, offices, retail and department stores, and warehouses are investigated for the seven districts of the CBD (Fig. 5), and the seven districts are classified into the following five specialized areas (Fig. 6): (1) the old international trade area (districts A and B), (2) the retail business area (districts C and D), (3) the new international trade area (district E), (4) the restaurant and amusement area (district F), and (5) the administrative and retail area (district G).
From these examinations, it can be concluded that the nucleus of the present CBD is the former foreigners' quarter and the import-export firms have played an important role in the formation of the foreign trade districts within the CBD.

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