The Principle of Similitude

Abstract

IT is rather curious that Prof, D'Arcy Thompson should refer to Tait's “Properties of Matter,” for I fancy I might claim some part of the credit for the paragraph in question. In a review of the first edition (NATURE, vol. xxxii., p. 314, 1885) I wrote:—“There is one matter suitable to an elementary work which I should be glad to see included in a future edition, viz., the principle of dynamical similarity, or the influence of scale upon dynamical and physical¹ phenomena. It often happens that simple reasoning founded upon this principle tells us nearly all that is to be learned from even a successful mathematical investigation, and in the numerous cases where such an investigation is beyond our powers, the principle gives us information of the utmost importance.”