REPORT ON METEOROLOGY. 
233 
6 th, In the course of this investigation, having selected the 
observations at Cumana and Toulouse, (both being places where 
the oscillation is positive ,) for obtaining approximate values of 
the constants in the formula, I found to my surprise and satis¬ 
faction, that from these observations alone, we might have in¬ 
ferred, a priori , not merely a negative oscillation in the arctic 
circle, but one not differing sensibly in amount from the actual 
observation of Captain Parry*. 
7th, I have determined from the formula the mean atmosphe¬ 
ric tide from the equator to the pole to be equivalent to the 
weight of a stratum of air 10^ metres in thickness; and the 
mean for the whole surface of the earth to be 16 metres, the 
air being considered under the usual pressure and temperature. 
I hope I shall be excused for dwelling so long upon this 
paper, as it contains not my own observations merely, but the 
results of all those which I could collect, made up to the present 
time, in every part of the globe. 
In the southern hemisphere, the excellent observations of 
Captain King at Port Faminef have given us the amount of 
the oscillation in a much higher latitude than any previous ex¬ 
periments. They correspond very well with my formula. 
With regard to the cause of this remarkable and very gene¬ 
ral phenomenon, extending from the equator to the poles, we 
are very much in the dark. We must be content to wait for 
much more complete information before hazarding conjectures. 
The connexion of it however with other meteorological changes, 
by whatever means related, seems certain. The diurnal cycle 
which it so strictly follows, and its modification by the seasons, 
show the influence of the sun. M. Bouvard’s views are cer¬ 
tainly so far correct, that temperature appears to be intimately 
connected with its variations. M. Dove, who is known by seve¬ 
ral essays on subjects connected with Hygrometry, has pointed 
out the connexion of the horary oscillations with the state of 
humidity of the atmosphere J; and Mr. Snow Harris of Ply¬ 
mouth has kindly put into my hands the results of a number of 
original experiments, which show in a very striking manner the 
diurnal changes in the force of the wind,—a subject quite in its 
infancy, and to which almost no attention is paid,—which cor¬ 
respond closely with the barometric oscillations ; the mean force 
of the wind being much greater at the period of afternoon 
minimum than at the morning and evening maxima. This is 
* See Art. 15. of the paper. 
f The observations are given in the Royal Geographical Society's Journal , 
No. I., and in my paper, Art. 21. 
X Poggendorff’s Annalen, 1831. 
