3. (Math.) Constituting a proportion; having the same, or a constant,
ratio; as, proportional quantities; momentum is proportional to
quantity of matter.
Proportional logarithms, logistic logarithms. See under Logistic. --
Proportional scale, a scale on which are marked parts proportional to
the logarithms of the natural numbers; a logarithmic scale. --
Proportional scales, compasses, dividers, etc. (Draughting),
instruments used in making copies of drawings, or drawings of objects,
on an enlarged or reduced scale.
Pro*por"tion*al, n. 1. (Math.) Any number or quantity in a proportion;
as, a mean proportional.