The most cursory examination of the wind records of the Ben Nevis Observatory shows that there is, even in fine weather, no strongly marked daily variation in their direction; nothing comparable to the land and sea breezes observed on our own coasts in summer. In order to see whether there was not some regular daily change concealed in the extremely variable winds actually observed, I reduced, by means of a traverse table, to north-south and west-east co-ordinates each observation during the summer months (June, July, August) of 1884 and 1885, taking account of the velocity of the wind as well as of its direction, so as to get the actual mean air motion at each hour of the day.