  Let $C_{i}$ ($\,i=1,\ldots ,N\,$) be the $i$-th open spherical cap of angular
radius $r$ and let $M_{i}$ be its center under the condition that none of the
spherical caps contains the center of another one in its interior. We consider
the upper bound, $r_{N} $, (not the lower bound !) of $r$ of the case in which
the whole spherical surface of a unit sphere is completely covered with $N$
congruent open spherical caps under the condition, sequentially for $i=2,\ldots
,N-1\,$, that $M_{i}$ is set on the perimeter of $C_{i-1}$, and that each area
of the set $(\cup _{\nu =1}^{i-1}C_{\nu })\cap C_{i}$ becomes maximum. In this
paper, for $N = 10$, we found out that the solutions of our sequential covering
and the solutions of the Tammes problem were strictly correspondent.
Especially, we succeeded to obtain the exact value $r_{10}$ for $N = 10$.
