Complex sentence: The text of the manuscript was collated by Tischendorf in 1843 and by Tregelles in 1846, thoroughly and independently, and compared their work at Leipzig for the purpose of mutual correction.
Split into simpler sentences: The text of the manuscript was collated by Tischendorf in 1843 and by Tregelles in 1846, thoroughly and independently. They compared their work at Leipzig for the purpose of mutual correction.