The Mean Lifetime of the Meson

Measurements of the lifetime of mesons which have traversed varying distances in air have been made and show that the value of $\frac{\tau }{\mu c^2}$ is constant. The existence of a spectrum of life-times is therefore excluded. The most probable value of $\frac{\tau }{\mu c^2}$ from our measurements is 2.6±0.3 × ${10}^{-14\mathrm{}}$ sec./ev.