12 the condition is even more restrictive: The rate of return k-1 must not be larger than w .loo p.c. whithin the range of wealth sizes in which the empirical data lie. The restriction is unavoidable because the Laplace transform in defined only for positive values of the argument of • For negative values the devinity f is by definition zero. If the argument is shifted to the right by Y the transform will be defined only for d ities of a rate of return below loo p.c. Similarly, for an argument of kW-Y the transform will be defined lr-1 only for rates of return below w .loo p.c. In reality, rates of return in excess of the limit given may exist. In thi3 case we can, however, always ensure that the above condition is fulfilled and the transformation (4) remains valid provided we make the unit of welath, W Q (Wo * 0) sufficient ly large. Indeed the condition x<« p ' 1 w y<w k (5> will be more easily fultilled if w and y are both measured in a large unit, because than their values will be both lower in the 3ame proportion, and that will automatically make it easier to fulfill the condition (5), if k<l. The choice of a large unit, however, will mean that the conclusions with regard to the distribution of income which are implied in (4)