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Rh The coefficients which Ross introduces are the measures of variation due to mortalifrjr, natality, immigration and emigration of the non-aflfected and affected persons respectively. From a set of equations containing these coefficients, the total population and the ratio of the affected to all its members, he gets an equation giving the proportion of the total popu- lation affected at a given time.^^ The curve of which this equation is an expression is, in the simplest case, the regular bell-shaped curve, in other words, the assumption that the inf ectivity ratio is constant or pro- portional to the number of persons affected gives curves which are not irreconcilable with the hypothesis of decline from exhaustion of suscep- tible material^ opposed by Brownlee. These studies in "à priori pathometry," still to be completed, give Ronald Ross a distinguished place in the modern English school of iatromathematicians.

In 1906, there appeared a little volume of verses with the title page "In Exile, by R. R. Privately Printed," of which the author says, in his preface.

i8

In a sympathetic review of this book. Dr. Weir Mitchell, a fellow medical poet, has said:

io

Of Ronald Ross's poems, space permits the citation of but one, the

17 Boss, Proc. Bay. 800. Lond,, 1916, Ser. A, XCII., 207; 211 et seq.

IS Ck>lonel Boss has recently presented to the Surgeon General 's Library his youthful dramas "Edgar" and "The Judgment of Tithonus" (Madras, 1S83), "The Deformed Transformed, '^ and the foUowing books of original verses, viz., "Philosophies" (1909), "Fables" (1907), "Lyra Modulata" (1911) and "The Setting Sun" (1912).

i» Mitchell, Jour. Am. Med. Ass., Chicago, 1907, XLIX., 852.