What does "sesquiplicate" mean?

Sesquiplicate: Subduplicate of the triplicate; -- a term applied to ratios; thus, a and a' are in the sesquiplicate ratio of b and b', when a is to a' as the square root of the cube of b is to the square root of the cube of b', or a:a'::sq. rootb3:sq. rootb'3. The periodic times of the planets are in the sesquiplicate ratio of their mean distances. Sir I. Newton.