ON THE REDUCTION OF METEOROLOGICAL OBSERVATIONS. 95 
(H,) Group B. of northern stations show a kind of transition state of the 
curves. The true culmination comes on much earlier (at midnight between the 
21st and 22nd), and the upward slope is much less steep, and shows signs of a 
minimum having been attained shortly before the commencement of the term. 
(H.) In the group C. this minimum comes clearly within the range of the 
observations, but at very different hours, viz. for 
St. Louis ,.......,..... at 3 P.M. M.T. at Station, 21st. 
Cincinnati Seige 5) 4) pin © ay elk BM 6 ” ” ry) » ” 
Western Reserve College., ,, 3 A.M., 3 5, 5 29nd. 
(H.) The minimum in question for St. Louis, falling nearly on the regular 
epoch of the afternoon minimum of the diurnal oscillations, is reinforced by it, 
and is very decided and well rounded. At Cincinnati this has not been the 
case; and a kind of struggle of tendencies seems to have taken place, marked 
by a double depression and abrupt intermediate elevation, At Western Reserve 
College the minimum we are tracing falling nearly on the gentler depression 
of the regular morning minimum, and being accompanied with less general 
movement of the mercury, forms a long fiat depression, ending in a gentle 
and continued upward slope extending beyond the limits of the term. 
(B.) This sheet presents three well-marked and distinct groups of curves 
in the United States. The most prominent is that of the eastern states, ex- 
tending from New York to Gardiner, Maine: here the apices occur about 
the same hour, but the minimum altitudes of the barometer were not observed, 
the first observation of each series being the lowest. 
(B.) The next group, namely, Western Reserve College, Cincinnati and 
St Louis, increases towards the west. The curves do not, however, present 
that similarity noticed in the eastern curves: the marked difference between 
the curves at Western Reserve College and New York indicates that the 
western limit of the eastern group passed between these stations. Again, the 
curve at Montreal being decidedly different from all the others, shows that 
the eastern group did not extend so far north. Observations are wanted to 
define the eastern limits of this group. 
(B.) Upon reviewing the projections it appears that the area included within 
a line passing from Baltimore north-east towards Quebec, inclosing Albany, 
from thence south-east to Gardiner, and thence south-west along the coast, 
passing New York and joining itself at Baltimore, and upon which are situ- 
ated the following stations, Baltimore, Albany, William’s College, Burling- 
ton, Montreal, Quebec, Gardiner, Maine, Boston, Providence, R. I., Middle- 
town, New Haven, Flushing, L. I., and New York, is characterized by the most 
complete systems of oscillation afforded by the group, the curves obtained at 
the above-mentioned stations more or less agreeing with each other. There 
are two principal lines of these stations, one from north to south, the other 
from west to east, or rather from south-west to north-east. 
North to South. South-west to North-east. 
Montreal. oo - Baltimore. 
Burlington. New York. 
Albany. Flushing. 
William’s College. New Haven. 
New York. Middletown. 
Flushing. Providence, 
Boston. 
Gardiner, Maine, 
