$\theta$ with respect to the shower axis, for two electron energies $E$ within $\Delta \, logE= 0.15$, at two lateral distances $r/r_M$ within $\Delta log (r/r_M)=0.1$, obtained from shower simulations with CORSIKA. Continuous curves - one primary proton shower with $E_0=10^{19}$ eV, dotted curves - average of 10 iron showers with $E_0=10^{17}$ eV; $s=1$. Independence of the primary particle’s energy or mass is seen. $\varphi=0$ means direction away from shower axis.[]{data-label="fig1"}](fig1N.eps){width="4.5in"}

![Distributions $f_{\varphi}(\varphi;r/r_M,E,s)$ as in Fig. 1 but away from shower maximum. Left column: $s=0.7$; right: $s=1.3$.[]{data-label="fig2"}](fig2aN.eps){width="3.6in"}

![Distributions $f_{\varphi}(\varphi;r/r_M,E,s)$ as in Fig. 1 but away from shower maximum. Left column: $s=0.7$; right: $s=1.3$.[]{data-label="fig2"}](fig2bN.eps){width="3.6in"}

Distributions of azimuth angles
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Figs 1 and 2 demonstrate the universality of the distributions $f_{\varphi}(\varphi;r/r_M,E,s)$ of the azimuth angle $\varphi$ of electrons with two fixed energies $E = 22$ MeV and $220$ MeV, at two distances $r/r_M$ for each $E$, at three shower ages $s = 1,\, 0.7$ and $1.3$. The distributions refer to *one* proton shower with $E_0=10^{19}$ eV and to the average of 10 iron showers with $E_0=10^{17}$ eV (actually the fluctuations from shower to shower for $E_0=10^{17}$ eV were not large, but for a better comparison with the proton shower we have averaged 