Complex sentence: The first steamboat on the River Ob, Nikita Myasnikov's "Osnova", was launched in 1844; but the early beginnings were difficult, and it was not until 1857 that steamboat shipping started developing on the Ob system in a serious way.
Split into simpler sentences: The first steamboat on the River Ob, Nikita Myasnikov's "Osnova", was launched in 1844. But early beginnings were difficult, and it was not until 1857 that steamboat shipping started developing on the Ob system in a serious way.