sentences:  On July 15 the brothers flew it for 45 minutes from Saint-Cloud to Meudon accompanied by M. Collin-Hullin and Louis Philippe II, the Duke of Chartres.The absence of a lifting gas release valve meant that the Duke had to slash the envelope to prevent it rupturing when they reached an altitude of about 4,500 metres (15,000 ft).It was not until after Meusnier's death that the first successful application took flight.