Proceedings of Royal Society of Edinburgh . [sess. 
88 
The Influence of High Winds on the Barometer at the 
Ben Nevis Observatory. By Alexander Buchan, LL.D, 
(Read March 2, 1891.) 
The question of the effect of wind on the readings of the baro- 
meter was first examined by Sir Henry James in a paper read to 
the Society on March 15, 1852.* The observations were made 
during the succession of gales from the south-west which occurred 
in January and February of that year, at his house in Granton, 
with an aneroid barometer, laid horizontally in succession on the 
table of his room in the cottage, on the seat of the open summer- 
house, and on the surface of the ground close to the summer-house, 
all at the same level. The anemometer employed was of a very 
simple construction, being on the same principle as the instrument 
used for weighing letters, the weight or pressure being indicated by 
the compression of a spiral spring in a tube. A table of results is 
added, giving the depression of the barometer in decimals of an 
inch for the velocity of the wind from 14 to 40 miles per hour. At 
14 miles the barometric depression was 0010 inch, and increased 
gradually to a depression of 0 045 inch at 40 miles per hour. Un- 
fortunately, the number of observations on which the depression for 
each wind-velocity has been deduced are not given, and the obser- 
vations in the cottage and those at the open summer-house are com- 
bined into one result. It may be safely assumed that the results 
arrived at indicate too large barometric depressions for the different 
wind-velocities as barometers are usually observed, namely, in 
houses. The depression on the lee side of any obstruction in the 
wind such as a summer-house is greater than it is in the room 
of a dwelling-house. Further, a barometer laid on the ground 
during strong winds will, if the wind brush briskly over the key- 
hole of the instrument, indicate a less pressure than that of the air. 
Since, however, in such a position, the wind will only at a few 
points have access to the connecting opening between the aneroid 
and the free atmosphere, it may be assumed that the instrument 
* Transactions , vol. xx. p. 377. 
