416 Proceedings of Royal Society of Edinburgh. [july 18 , 
7. The Thermal Windrose at the Ben Nevis Observatory. 
By A. Bankine. 
The Table, showing the Thermal Windrose, accompanying this 
paper, was computed from the observations made at the Ben Nevis 
Observatory during the three years ending May 1887. It shows 
the mean temperatures, on the mean of the three years, of the 
different winds for each month, for the year, and for the seasons. 
The direction of the wind is observed to the thirty -two points of the 
compass, but in this table the temperatures are only shown for eight 
points, the intermediate points having all been added on to these 
eight points in the same way as that described by Mr Omond inh is 
paper on “Winds and Rainfall” in the Journal of the Scottish 
Meteorological Society , namely, the by winds were added to their 
adjacent octants, and the points half-way between the octants were 
on the odd day of each month added to the octant to their right, 
looking out from the centre of the compass card, i.e., they were veered 
two points, and on the even days to that on their left, i.e., they were 
backed two points. The mean temperature of each direction of wind 
for each month was found by tabulating the hourly observations of 
temperature under the direction of wind observed at the same time, 
or under its octant as above, and then taking the arithmetical mean. 
When the wind was variable, or its direction doubtful, the tempera- 
ture was entered in the column for calms and variables. These 
variable winds belong chiefly to the northern half of the compass, 
their existence being principally due to the abrupt and precipitous 
character of the north side of the Ben. The temperatures given in 
the table are those indicated by thermometers which in summer 
and autumn are protected in the regulation Stevenson screen, and 
in winter and spring in a smaller pattern of the same, which can 
he shifted up or down a ladder-like stand, so as to be always at or 
near the standard height of 4 feet above the surface of the snow. 
There are two columns of monthly means in the table, one giving 
the mean temperature for each month, deduced in the ordinary 
manner from the daily means, and the other giving the mean of the 
temperatures in the table under the eight wind directions. It will 
be seen that there is a considerable difference between these mean 
