Abel-Ruffini Theorem/Historical Note

Historical Note on Abel-Ruffini Theorem
The Abel-Ruffini Theorem, on the general insolubility of the quintic by radicals, was stated by, who built an incomplete proof in $1799$.

This was published in his two-volume work.

provided the first complete proof in $1823$.

He published this in a small pamphlet ($1824$) at his own expense. He sent a copy of this to, but for some reason put it aside and never opened it. Thus never had cause to visit  and the pair never met.

It later transpired that had independently proved this theorem some years earlier, in a work that was not published in $1846$, some $25$ years after his death.

Moreover, analysis of the problem also gave a complete answer to the question of which equations are solvable in radicals and which are not.