ON ATMOSPHERIC WAVES. 117 
of the barometer on a large scale, of a somewhat similar character to that of 
the great November wave. The oscillations on each side the central maximum 
June 3: 22 have evidently a symmetrical relation, and are to be distinguished 
from the monthly maxima before alluded to. It is highly probable that a 
further examination of the Toronto observations will furnish us with the Ca- 
nadian type of atmospheric waves, in the same manner as Sir John Herschel 
found various continental types, and that in some localities (Hanover for in- 
stance) the barometric curves were exceedingly anomalous, arising most pro- 
bably from an interference of different systems of waves. It is also pro- 
bable that a further examination of the Greenwich observations relative to 
the monthly maxima will develope the corresponding British type, and that 
an investigation of the greater symmetrical movements will conduct us to 
phenomena of a highly interesting character. 
Directions of Waves. 
The apparent regularity of the flowing of these waves, has induced the 
hope that by a more detailed examination of the transits of the maxima at 
distant stations, a tolerable idea may be formed of the direction in which 
they move, and thus a step may be gained in ascending to their causes. If 
we take Greenwich, Prague and Munich, as three stations, the order of transit 
will vary, as the direction of the axis of translation of each wave varies. 
The following appear to be some of the phzenomena presented by waves mo- 
ving in different directions. 
I. Waves from W.N.W., or nearly so.—The crests will first pass Green- 
wich, and at a considerable period after they will pass Munich and Prague; 
these stations they will pass about the same time; Munich and Prague will 
therefore have simultaneous maxima. 
II. Waves from 8.W.—The crests will pass the stations in the following 
order: Greenwich, Munich, Prague. 
III. Waves from S.S.W.—The crests will pass Greenwich and Munich 
simultaneously, and afterwards Prague. 
IV. Waves from S. by W.—The crests pass the stations in the following 
order: Munich, Greenwich, Prague. 
V. Waves from $.—The crests will pass the stations nearly at the same 
time. 
VI. Waves from S.S.E.—The crests pass the stations in the following or- 
der: Munich, Prague, Greenwich. 
The fact that numerous systems of waves traverse Europe at the same time 
renders it very difficult to determine the intervals between the transits of two 
successive maxima of the same system ; the only mode appears to be, to ar- 
range all the maxima and minima, and to classify and examine those that are 
moving in the same direction and that transit the stations under the same 
circumstances. 
Table V. exhibits the maxima and minima that passed Munich between 
the transits of two minima, which apparently marked the passage of the an- 
terior and posterior troughs of a normal wave; the altitudes are converted 
into English inches and reduced to the level of the sea. 
During this period we find three maxima from the §.S.W.; the intervals 
between them are nearly equal ; the first 104 hours, and the second 97 hours. 
The middle wave is the highest, 30°667 ; those on each side are nearly of the 
same altitude 30°304 and 30275; the central wave is the highest of the series, 
which opens with a small wave from W.N.W. Table VI. exhibits the features 
of this wave. 
