Abstract
The most probable value of Planck's Constant h has been computed, together with the probable error. The latest value of each of the other constants appearing in the equations has been used; and the probable error in each has been taken into consideration. The mean value from seven distinct methods is (6.5543 ± 0.0025) × 1027 erg. sec., and each of the seven residuals lies within the limits of error. The indicated error in the final mean is practically exclusive of any error in e (assumed 4.774). However, by assuming Lewis and Adams' theory of ultimate rational units, it is possible to compute, in a number of different ways, an independent value of e, or of h. One such computation, using Blake and Duane's X-ray data, yields e=4.7705±0.0046, h=6.550±0.0I3.