抄録
It is clear from the equation of motion of elastic medium expressed in vector form that there are several different solutions (expressions) which satisfy the condition Δ=0 (§3).
In this paper, 8 different expressions (at least 4 of which are mutually independent) are obtained (§4). Next, by using one of these solutions, the author got two independent solutions for a problem of motion in an infinite elastic medium when displacements (or stresses) are given on the wall of a cavity in that medium (§5). In such a problem it is proved that we cannot get unique solution as long as we use the so-called Sezawa's solution ((17), (18), (4)) only (§6).
