of Edinburgh, Session 1885 - 86 . 
841 
tions a considerable error is thus introduced, especially at the higher 
velocities. To reduce this error as far as possible, I have only 
taken those days in summer in which no wind of over force 3 (21 
miles an hour) was recorded. This practically picks out all the 
fine days, and on these days the daily variation might be supposed 
to be better marked than during stormy weather. In the summer 
of 1884 there were 27 such days, and in that of 1885, 47. Along 
with each day was included the observation of the previous mid- 
night, so as to have the data for correcting the residual inequality 
in the means. For 1884 the mean air motion for the whole day 
was from about S.W. by S., and for 1885 from W.N.W. The 
mean winds at each hour, however, differed much from these, and 
in spite of the difference between the days’ means in the two years, 
the hourly means agreed substantially with each other, both in 
direction and velocity. The two years were therefore added 
together, the mean wind for the day then coming out as W.S.W., 
and of very small velocity, only about 1J miles per hour. By 
