382 CORRECTION TO BAROMETER FOR FORCE OF WIND. 
in them, as in the above experiments ; and this view is further confirmed by the 
fact, that if a window or door exposed to the wind is opened in any room in which 
there is a barometer, the mercury is raised, shewing that the air is compressed in 
the room, as it is in Lesuie’s cylinder, when we blow through the larger tube. 
So also the barometer is elevated by the compression of the air on the windward 
side of the summer-house, whilst it is depressed on the leeward in proportion to the 
force of the wind and the intermittent gusts; but the effect in a room, the doors 
and windows of which are usually closed on the windward side, is to produce a 
depression. We may also infer, but I know of no experiments to support the 
opinion, that during gales of wind the barometer would stand at a higher level on 
the windward side of a hill than on the leeward, the points of observation being 
at the same altitude. The known discrepancies between the heights deduced from 
the indications of the barometer during high winds and calms, are, however, most 
probably due to this cause. 
Professor DANIELL, indeed, suggests this very question, ‘“‘ Whether local cur- 
rents of air, and those deflections of the wind which are caused by the different 
directions of different valleys, may not produce various partial adjustments of 
density which may have an influence upon barometrical measurements ;” and 
in the experiments which he made for determining the altitude of Hedley Heath, 
by observation at different stages of the height, he found an error of 7:5 feet in 
157 in the height of the station in a ravine; he says, “ omitting the second result 
(the one in the ravine) all the rest are correct, and the third is deficient ex- 
actly the quantity which is in excess in the second ;” it is, therefore, obvious 
that the configuration of the ground was the cause of this anomaly. It is much 
to be regretted that Professor Danrett had not followed up the inquiry; but he 
concludes his remarks by putting the following question :—‘ What is the effect of 
wind upon barometrical mensurations? If I had the means of prosecuting these 
_inquiries in the complete manner which the nicety of the subject requires, I would 
not have suffered them to retain the form of crude speculation.” 
By a repeated series of comparisons at Granton, I obtained the following 
results; but I wish them to be considered as merely approximate results, to which 
I desire to draw the attention of meteorologists, that those who are stationed in 
countries subject to violent storms and hurricanes, may supply us with the amount 
of the depressions, corresponding to higher velocities of the wind than I have been 
able to supply, and that thus the law connecting the amount of depression with 
the velocity or pressures at different stations may be established. ‘The effect of 
the wind when blowing from different quarters will also have to be studied, that 
the amount of the corrections necessary to be applied to the observed height of 
the barometer at any particular station, when the wind blows from any quarter, 
may be known. 

