120 REPORT—1846. ; 
vestigation of these waves, especially that of November. The mode of in- 
vestigation and the partial results arrived at during the period between the 
sittings of the Association in 1843 and 1844 form the subject of my first re- 
port, which, as before stated, must be regarded only as a fragment. 
During the further investigation of the wave of November various obser- 
vations came to hand, which appeared to throw considerable light on the 
general character of atmospheric undulations. The publication of the Green- 
wich and Toronto observations afforded an interesting comparison of the 
passages of certain maxima at these distant stations, and by extending this 
comparison to Prague and Munich, several interesting features of certain 
secondary waves during the transit of a supposed normal wave appeared so 
clearly to be made out, that it was deemed desirable to include the whole of 
this comparison in the succeeding report, rather than run the risk of its being 
lost by deferring it until after the examination of the great wave should be 
completed. Another most interesting result arrived at about this time, was 
the recurrence of the great wave of November. The return of this interest- 
ing phzenomenon appeared so strikingly distinct in 1843 and 1844, that to 
have omitted noticing it in the Report would have greatly contributed to re- 
tard the inquiry. It accordingly forms the second section of the Report of 
1845. These circumstances, with the further investigation of the great wave 
of November 1842, give to the second report a more fragmentary character. 
Previous to entering on the immediate subject of the present report, it will 
be desirable to review the steps that have been taken for observing the great 
symmetrical wave on its return in 1845; and also to notice any other cir- 
cumstance that may have transpired during the past year at all calculated to 
throw any light on the subject of our investigations. With regard to the first 
point, certain instructions were drawn up, which were forwarded to gentle- 
men interested in meteorological research, and otherwise circulated, in con-. 
sequence of which a number of interesting and valuable observations were 
obtained. The results of the examination of these observations, as far as it 
has yet proceeded, will form the first part of the present report. In the Phi- 
losophical Magazine for April in the present year Mr. Brown published a 
voluminous paper on the oscillations of the barometer, with particular refer- 
ence to the meteorological phenomena of November 1842, the month in 
which I first observed the great symmetrical wave. This paper is accom- 
panied by diagrams representing the direction of the wind in England, Scot- 
land and Ireland every day, from the Ist to the 26th inclusive. Upon a very 
careful perusal of it, I found that the observations, as given in the diagrams, 
very beautifully illustrated Prof. Dove's theory of parallel currents or alter- 
nately disposed beds of oppositely directed winds, and appeared to throw so 
clear a light on the real character of the atmospheric undulations, that I was 
induced to enter upon a very careful examination of the barometric obser- 
vations in connexion with the diagrams of the wind. The result of this ex- 
amination has been to give the inquiry a completeness which it was before 
destitute of. It was previously difficult to define the real notion we formed 
of an atmospheric wave ; not so much from the distribution of pressure over 
a tract of country gradually decreasing on each side a line of maxima, as 
from the relation of the aérial currents or winds to this distribution of 
pressure of which we were to a certain extent ignorant. The examination 
of these observations has exhibited very clearly the distribution of the aérial 
currents in relation to the distribution of pressure, and enabled us to define 
the nature of an atmospheric wave both as regards its undulatory and mole- 
cular motion. This definition, with the examination of the observations, 
forms the second part of this report. 
