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r=0®) which is an impossibility. This impossibility disappears, 
however, if 6’—0O, whence I think may be concluded, that in this 
case, as with an infinitely extended liquid, the motion can never 
be aperiodic, but that the limit of periodicity consists in an infinitely 
slow stationary motion (M= 0)®). 
1) This is also the case with ZemePLÉN's equation (13) (loc. cit.) which was 
arrived at by taking as a boundary condition not that the amplitude u, is finite 
at the centre, as was ZeMPLÉN's intention, but that «gr? is finite; in this case, 
therefore, uw, itself can become infinite. 
2) In that case w=a (vid. § 23 of Comm. 148); Zemprén’s formula (13) is 
reduced to the same equation by taking m (i.e. 5" in our equations) infinitely small. 
