This disadvantage of the resistance of surface was very manifest in the earlier experiments with navigable balloons, when only feeble motive power was available. For instance, in Count Zeppelin’s experiments in 1900, his two motors of 16 h.p. could not combat a greater wind force than about three metres a second. Then airships could indeed only be called toys. It has only been possible to make them partially successful concerns by enormously increasing motive power. At the h.p. figures with which the latest made large airships have been endowed, the wind limit is much lower than in the case of the heavier-than-air constructions. Though now airships can encounter moderate winds, they are still fair-weather instruments. For the great records of distance established by Count Zeppelin favourable meteorological conditions have been wisely selected. It was M. Santos Dumont who first led the way in making airships something beyond toys. He, in his picturesque and world-alluring experiments, first dared to encounter winds which in force exceeded what would be called calm weather. It is exceedingly difficult to ascertain what are the exact wind forces overcome by a body moving in air. The measurements have to be taken from a point independent of the moving body. We generally find this one important figure omitted in accounts of airship voyages. M. Santos Dumont’s experiments gave especially favourable opportunity for ascertaining correct records of the wind forces overcome. Since M. Santos Dumont so frequently rounded the Eiffel Tower close to the storey where the meteorological instruments were placed, the writer obtained from the authorities of the Eiffel Tower a record of the wind forces registered on all the days of his experiments. A comparison of those records with those of M. Santos Dumont’s journeys made it possible to approximately ascertain the highest wind forces he combated on his journeys round the tower; these were about five metres a second. M. Santos Dumont, however, appears to have claimed six metres a second for his highest wind record. The brothers Lebaudy in their earlier experiments about doubled the record of Santos Dumont in this respect. As time has gone on greater advance has been made, though the limit is still represented by moderate wind. There is, perhaps, some consolation in this thought for those who fear raids of an inimical airship fleet. The proverbial windy nature of our favoured islands is perhaps even more protection than darkened cities and artillery shot, though it is well indeed not to neglect the two latter precautions.