Complex sentence: But Bessemer was able to maintain them intact without litigation, though he found it advisable to buy up the rights of one patentee, and in the case of Mushet was assisted by the patent being allowed to lapse in 1859 through non-payment of fees.
Split into simpler sentences: But Bessemer was able to maintain them intact without litigation, though he found it advisable to buy up the rights of one patentee. In the case of Mushet, he was assisted by the patent being allowed to lapse in 1859 through non-payment of fees.