Fig. 63. Motor of the Wright biplane.

Besides guiding the aerial traveller on his way some means must be devised of conveying useful information to him. It will often be of great importance to know the strength and exact direction of the wind. Skimming the air at the rate of fifty miles an hour, the aviator will find it difficult if not impossible to make these observations. The German Aerial Navy League has suggested that special light-houses be constructed for that purpose. These are to send a long beam of light in the direction in which the wind is blowing. For day flights it will probably be necessary to have a long arrow painted white and swinging on a pivot so that it can be turned in the proper direction.