What is "proportional scale"

Proportional \Pro*por"tion*al\, a. [L. proportionalis: cf. F. proportionnel.]

1. Having a due proportion, or comparative relation; being in suitable proportion or degree; as, the parts of an edifice are proportional.
   --Milton.

2. Relating to, or securing, proportion.
   --Hutton.

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.