On Physically Similar Systems; Illustrations of the Use of Dimensional Equations

摘要: I. The 3fosi Genera/Form of Phys~ ca/Equations.—Let it be required to describe by an equation, a relation which subsists among a number of physical quantities. of n different kinds. If several quantitics of any one kind are involved in the relation, let them be specifie by the value of any one and the ratios of the others to this one. Theequation will then contain n symbols QI~. Q „, one for each kin «l of quant. ity, and also, in general, a number of ratios r', r", ctc., so that it may bc written f ('QI g..-Q r'r"..)= o Let us suppose, for the present only, that …