Complex sentence: On 8 August 1901, during one of his attempts, his dirigible began to lose hydrogen, and started to descend and was unable to clear the roof of the Trocadero Hotel.
Split into simpler sentences: On 8 August 1901, during one of his attempts, his dirigible began to leak hydrogen gas. It started to descend and was unable to clear the roof of the Trocadero Hotel.