There have been made public many papers on the roundness of gravel, but no work has so far been done on various sizes of gravels over a long distance in field. However, in order to make clear the relations between roundness and transportational agency it is necessary to investigate these factors. The purpose of this paper is to clarify the change in roundness of various sizes of pebbles over a distance and the relations between roundness and size in particular stations.
The investigation was made in the river-bed of the Tanla River extending over about 60km. from Hikawva to Futako-Tamagawa and 12 sampling stations were selected there. The mathod of measuring is as follows: First samples are divided into four clesses, those of 61_??_. 32_??_. 16_??_. and 8_??_mm. in diameter respectively, and next, about 150 graywacke pebbles of each class were photographed and then the roundness was measured by the method developed by Wadell. The results are as follow:
(1) The number of pebbles necessary for measuring mean roundness was determined in the following way. At Ome, where the frequency of roundness seems to be most complex, the relations among number and mean roundness and confidence interval were elucidated (Tab. 1). The table shows that the smallest number with small confidence interval is approximately 150.
(2) The roundness of pebbles is not always the function of transported distance as shown in fig. 2. Where the detritus from valley walls are mixed with transported gravels in the upper reaches, the roundness decreases abruptly. The location where the roundnesss suddenly decreases is different according to pebble size. For the size of detrital materials differs according to the density of crack or joint spacing which differs as the outcropping locality differs.
(3) In the lower reaches there are locations where the roundess of pebbles increases abruptly. The location where the roundness increases abruptly lies in comparatively upper streamn in case of larger pebbles and in comparatively lower reaches incase of smaller pebbles. It is probable that laorger rabbles change first the mode of heir downward shifting by decrease of the gradient of river course and friction acts on them earlier than it does on smaller pebbles.
(4) The relation between size and roundness is not always expressed as y=mxn, where y is roundness, x is size, n is a coefficient, and. in is a constantas shown in fig. 3. In the upper reaches where the detritus from the valley walls are mixed with river gravels, no relation like this can be found or the converse relation is observed. At each sampling station in the river-bed from Ome to Futako-Tanzagawa, roundness of pebbles of 8_??_4mm. in size is remarkably lower than that of larger pebbles. This fact suggests that pebbles of a size of 8_??_4mm. are transported by saltation, while the larger pebbles by rolling or sliding in the reaches above-mentioned.

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The retail shops in a city are divided into groups of two kinds, the central group and non-contral ones. Each shop group has its trade area, that is, the distribution area of customers or the distribution area of goods sold at shops in the group. The trade area of the shopping center of a city covers a wide area which often embraces the neighbouring towns and villages While the respective trade area of non-central shop groups covers only. a limited area in the city and usually overlaps to each other.
The writer at first theoretically treated the trade area of a non-central shop group and subdivided the area into the following three: (a) the area most closely connected to a shopping street, (b) the intermediate area and (c) the area most loosely tied to a shopping street. If two oriaore shopping streets were closely situated or intersect to each other, such combinations are to be seen as (a, a), (b, b), (c, c), (b, c), etc. in the ovelap of their trade areas. In the second place, taking the northern part of Ryato city as his field, the writer, surveyed the trade areas of four shopping streets running parallel and intersecting to each other in order to compare them with theoretically defined trade areas. The special features in shape and extension of the overlapping trade areas as the deviation from the theoretical cases were explained as the effects of non-proportioned distribution of the shopping streets to the residential areas, difference in drawing power for customers which depends mainly upon the density of shops and how many different kinds of shops are there in respective shopping street, and sporadic exsistence of .permanent retail markets in the area surveyed.

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The regions along the Japan sea coast have continuous snow cover in winter as shown in Table I (Thickness of snow cover in the average year is indicated in the upper line and that in winter of 1951_??_52 in the lower line). In these regions, bus services are suspended for a certain period in winter. Examining the daily thickness of snow cover at 185 stations in the regions and date of suspension and reopening of bus services, the writer concluded as follows.
1) Bus service is generally brought to a standstill if the snow cover became thicker than 50cm and is reopened if it became less than 50cm. thick.
2) In case of busy routes, however, bus is served even though the snow cover is thicker than 50cm. In very busy, wide and paved roads, bus service does not come to a standstill even though the snow cover became thicker than 120cm. But in little frequented, narrow and bad roads, bus is not served throughout the snow-covered period.
3) In most of the comparatively warm but heavily snowing regions, snow fon the roads is removed by labourers in the early thawing season. In cold regions like Aomori prefecture and the northern part of Akita prefecture, only the snow on very busy bus routes is removed, and that on many other routes is left un-touched. Because, in cold regions, snow on the roads compactly settles as it increases in thickness, so sleighing and bus traffic are possible. But in comparatively warm regions, heavy transportation is impossible during snowy season, so the demand for transportation repidly increases in thawing season. Hence the necessity of removal of snow by many labourers.

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A comparative study was made on roundness and composition of the sand in the river bed of the following three rivers in Kanto district: the Tamagawa flowing out from Palaeozoic region, the Tsuruznigawa from Tertiary and. Dilu-vial region and the Koisegawa from igneous rock region. The results are summerized as follows:
1) The roundness of sand generally increases as the transported distance increases. But the comparative study revealed that (a) in the river from igneous rock region, sand has a roundness of comparatively low degree and contains much mineral grains, (b) in the rivers from sedimentary rock region, roundness of sand is high and less mineral grains are contained.
2) Grouping the sand into two classes, sand of 2_??_4mm in size and sand of<2min, and the increasing degree of roundness in relation to the transported distance was. examined respectively. Roundness of the sand of 2_??_4mm. considerably increases as it is transported, but that of the sand of<2mm. changes only slightly. So, in order to investigate the the factors in change of roundness of the sand smaller than 2mm., it is necessary to subdivide the classification of sand done by Krumbein and Wentworth.

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