Now, suppose that the note produced with Savart's apparatus is in unison with A3, when the experimenter turns round the first wheel at the rate of 60 turns per minute or one per second, and that the **circumferences** of the various multiplying wheels are such that the rate of revolution of the toothed wheel is thereby increased 44 times, then the latter wheel will perform 44 revolutions in a, second,.

In the first series of circles, reckoning from the centre the openings are so made as to divide the respective **circumferences**, on which they are found, in aliquot parts bearing to each other the ratios of the numbers 2, 4, 5, 6, 8, 10, 12, 16, 20,.

Rectification and quadrature of the circle have thus been, since the time of Archimedes at least, practically identical problems. Again, since the **circumferences** of circles are proportional to their diameters - a proposition assumed to be true from the dawn almost of practical geometry - the rectification of the circle is seen to be transformable into finding the ratio of the circumference to the diameter.

The average weights, heights and head **circumferences** were plotted on graphs; these curves were named the 50th percentile on each chart.