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 During the whole trip my greatest altitude was 105 metres (346 feet). Taking into consideration that my guide rope hangs 40 metres (132 feet) below me, and that the tops of the Bois trees extend up some 20 metres (70 feet) from the ground, this extreme altitude left me but 40 metres (140 feet) of clear space for vertical manœuvring. It was enough; and the proof of it is that I do not go higher on these trips of pleasure and experiment. Indeed, when I hear of dirigibles going up 400 metres (1300 feet) in the air without some special justifying object I am filled with amazement. As I have already explained, the place of the dirigible is, normally, in low altitudes; and the ideal is to guide-rope on a sufficiently low course to be left free from vertical manœuvring. This is what M. Armengaud, Jeune, referred to in his learned inaugural discourse delivered before the Société Fraçaise de Navigation Aérienne in 1901, when he advised me to quit the Mediterranean and go guide-roping over great plains like that of La Beauce. It is not necessary to go to the plain of La Beauce. One can guide-rope even in the centre of