The customary school method of dealing with logarithms (i.e. the initial definition : if ax =N then …) has one great defect : it gives no lead whatever towards the higher theory of logarithms, nor even towards methods for calculating them. “How shall we introduce our sixth form girls to the theory?” a mistress recently asked; “it seems to come like a bolt from the blue.” Klein has some true and forcible things to say on the subject [Elementar Mathematik vom höheren Standpunkte aus, (3 ed. 1924) I, p. 155 et seq.] from among which a sentence or two may be quoted.