Set one of the numbers upon c to the same number upon d ; and against the other number upon c is the mean number or side of an equal square upon d.

Required the mean proportion between 20 and 45.

Set 20 upon c to 20 upon d ; and against 45 upon c is 30 upon d.

To cube any number, set the number upon c to 1 or 10 upon d; and against the same number upon D is the cube number upon c.

Required the cube of 4.

Set 4 upon c to 1 or 10 upon D; and against 4 upon d is 64 upon c.

To extract the cube root of any number, invert the slide, and set the number upon b to 1 or 10 upon D: and where two numbers of equal value coincide on the lines b d, is the root of the given number.

Required the cube root of 64.

Set 64 upon b to 1 or 10 upon d ; and against 4 upon b is 4 upon D, or root of the given number.

On the common rule, when 1 in the middle of the line c is set opposite to 10 on d, then c is a table of squares, and d a table of roots.

To cube any number by this rule, set the number upon c to 10 upon d; and against the same number upon d is the cube upon c.