瀬戸内海底質の硬軟に就いて-I : 浅海用新型Penetrometer

概要

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In many ecological studies of the burrowing fauna and the problems of dredge fisheries the quantitative information of hardness or depth of the marine soil in shallow waters is required. The present author designed a new penetrometer for this purpose, taking into consideration (i) low cost, (ii) simplicity of operation, (iii) rapidity in measurement regardless of sea depth and (iv) Applicability undto tough field conditions. Fig. 1 shows the structural details of the new designed penetrometer. It may be divided into 3 parts as follows: the penetrative portion, slider or depth-measuring-portion and holding portion. The apparatus is 7.4kg. in weight (5.5kg. in water), and about 127cm. long. The results of the hardness measurements are shown in Table 1. A tendency of considerable dispersion of values of penetration is seen where the penetrating value is as shallow as about 30cm., but in the range from 40cm. to 80cm. the replication error at one station is very small. Falling spead in water range of 10-40m. depth was to be almost constant in 1.62m./sec. as shown in Fig. 2, so the values of penetration can be observed directly compared.