i 
R- 
ON ATMOSPHERIC WAVES. ‘113 
and their intervals; also the determination of the direction in which they move, 
from observations at the three stations, Greenwich, Prague, and Munich. 
Qnd. Of the recurrence of the symmetrical wave observed in November 
1842, in November 1843, and October 1844, with the mean wave deduced 
from combining the three. 
3rd. Of an extension of the investigation of the waves A 1 and B 1, forming 
the subject of the last report. This portion is confirmatory of the views then 
advanced, and will include evidence of the existence of two larger waves on 
which those noticed last year were superposed. 
. Section I. 
Rise of the Barometer above 30 inches. 
In Table IV. of the abstracts of the results of meteorological observations 
made at the Royal Observatory, Greenwich, 1840 and 1841, Mr, Airy has 
shown that in every month the barometer rose above 30 inches. The same 
result is shown in Table V. of the abstracts for 1842. The observations made 
at the Colonial Observatory at Toronto indicate the same general fact ; in 
every month during 1841 and 1842 the barometer rose above 29°750. ‘The 
altitudes, when reduced to the level of the sea, agree with those at Greenwich, 
showing a rise on both sides of the Atlantic above 30 inches in every month. 
When, however, the dates of the maxima at the two stations are compared, 
-we find in almost all instances considerable difference, that is, the absolute 
maxima at both stations are generally several days’ interval from each other. 
On turning to the daily records of barometric pressure at both stations, we 
find maxima occurring at but few days’ interval from each other, so that cor- 
responding to the greatest altitude for the month at one, we obtain shortly 
before or after a maximum at the other. This leads us to a fact of a very 
interesting nature, and one that is generally borne out by the Greenwich ob- 
servations, namely, that ¢wice in each month the barometer passes a maximum 
above, or but very slightly depressed below 30 inches, but more usually above. 
Upon subjecting the Toronto observations to a closer scrutiny and clearing 
them from every extraneous influence, so that the pure gaseous pressure may 
alone be contemplated, the rise to this gauge-point (30 inches, or with the 
tension of the aqueous vapour deducted 29°900) is much more frequent, and 
there are but few exceptions to the general fact, that the pressures at the 
epochs of maxima are confined to small excursions, seldom amounting to *1 
inch above or below the mean—30°030, including those observations that 
are evidently of an extraordinary character—29°983, excluding them and the 
lower readings marked (+) in the following Table, which includes all such 
_ maxima observed at Toronto during the period of the regular flowing of the 
waves at Greenwich, hereafter to be noticed. The observations, as recorded 
in the volume of Toronto observations, have been reduced to the level of the 
sea ; the tension of aqueous vapour has been subtracted in each case, and the 
gaseous pressures resulting have been corrected for the diurnal and annual 
oscillations as determined from the two years’ observations. During the pe- 
riod embraced by the table at the station Toronto, the gaseous pressure 
appears to have passed a maximum about or not far removed from the 3rd 
_ of each month, and another about the 16th or 17th; intermediate maxima, 
5, 
about the 10th and 27th, have also been observed, but with less regularity. 
From observations made during so short a period at only one station it would 
be premature to draw any conclusions. It however appears very desirable that 
some approximation to the Canadian normal wave should be attempted, by 
combining the observations in a manner somewhat similar to that which I 
- part of this report). 
i 1845. I 
ey adopted with regard to the great November wave (see the second 
