
(MST RNG 
XXIII.—On a Necessary Correction to the Observed Height of the Barometer de- 
pending upon the Force of the Wind. By Captain Henry James, R.E., 
F.R.S., M.R.LA., F.G.S., &e. 
(Read 15th March 1652.) 
The oscillations of the barometer during gales of wind must have been noticed 
soon after the invention of the instrument by TorRIcELLI 200 years ago. Every 
observer is familiar with the fact, that the barometric column is continually 
rising and falling during gales; and we frequently meet such observations as 
“ Barometer very unsteady,” in Meteorological Registers. 
In Sir Witt1aAm ReIp’s work on the Law of Storms, he says, “during the 
hardest part of the gale (the Bermuda hurricane of 1839) several persons ob- 
served remarkable oscillations of the mercury in the tubes of the barometers ;” 
and in a letter which I had the honour to receive from the Astronomer-Royal, 
Professor Atry, in reply to one from myself on this subject, he says, “ I think (but 
am not certain) that the depression of the barometer at every gust of a gale of wind 
‘is an ordinary phenomenon, without reference to the position of the barometer with 
regard to the direction of the wind. Many years ago I was in the observatory of 
Marseilles during the blowing of the Mistral (a wind well known there), and there 
I saw the drop of the barometer at every gust in great perfection. I do not 
remember the position of the barometer.” 
I am not aware that the cause of this unsteadiness of the barometer has been 
hitherto investigated by any one, or that the amount of the depressions has been 
shewn to depend upon the force of the wind. 
My attention was particularly drawn to this subject last December, by observ- 
ing that during the heavy gale of wind which we had on the 7th and 8th of that 
month, the barometer was always depressed at each gust of wind, and that, as far 
as I could judge by the ear, by listening to the rush of the wind round my cottage 
at Granton, the amount of the depression was in some proportion to the force or 
velocity of the wind. 
My cottage, which stands alone on a height overlooking the Forth, is pecu- 
liarly well situated for investigating this question; and the succession of gales 
from the south-west which we had during the months of January and February, 
afforded me the opportunity for following up this inquiry, to confirm my previous 
impressions, and to give approximately the depression of the barometer corre- 
sponding to the different amounts of the pressure of the wind. 
The barometer used in these experiments was an aneroid, which from its being 
80 portable, and requiring no other adjustment than to be laid horizontal, was 
VOL. XX. PART III. 5K 
