In Bolzano›s correspondence with the Royal Bohemian Society of Sciences there are, among other things, a long expert‹s report on the problem of solving algebraic equations higher than those of the fourth degree und several reports on Christian Doppler’s work in physics. In the last two essays, Bolzano puts Euclidean geometry on a topological foundation. His remarks culminate in a particular case, Jordan’s famous curve theorem, for which there are various ideas for proof in Bolzano’s manuscripts.