In term s of y the critical value is y = 1-33. (5-31) Hence if y > 1-33 the point of separation occurs for a finite t = t8, i.e. when x8 = ta/M%, and approaches the origin as M0->oo. I f y< 1*33 th an infinite value of t. Hence from the conclusions of and (6), in te probably occurs a t a non-zero distance from the leading edge. The critical values of y determined in the first two parts of § 5 were 1*4 and 1-35 respectively. Hence both methods discussed above overestimate the point of separa

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... for large M0, and in view of the discrepancy between their estim ation point, the Karman-Pohlhausen m ethod m ust be discarded for retarded flows. In conclusion, I should like to thank D r L. H ow arth m ost sincerely for his help and guidance during the writing of this paper.