EF. Loomis— Observations of the U. 8. Signal Service. 5 
March, 1877. The total number of these cases is 89, and the 
are shown in Table I, in which two lines are given for eac 
date; the first horizontal line shows the direction and force of 
observations. For each case, the date of minimum pressure at 
the neighboring surface stations is indicated by an asterisk. 
It will be noticed that for several observations preceding the 
minimum pressure, the surface winds generally blew from one 
of the points §., S.E., E. or N.E.; and that about the time of 
minimum pressure the wind changed to one of the points N., 
-W., W. or S.W. For convenience I call the semicircle in- 
cluding the four former directions the east quarter, and the 
semicircle including the four latter directions the west quarter. 
On the summit of Mt. Washington we sometimes notice a 
similar change of wind near the time of minimum pressure, but 
not invariably. ‘There are two cases in which the change of 
wind from one of the above mentioned quarters to the other 
did not occur in a decided manner either at the base or summit 
of Mt. Washington. These cases are Nos. 48 and 72. In each 
of these cases however there were a few of the surface stations 
at which the wind blew for a short time from the east quarter. 
Tn No. 48 at 9.2 the wind at Boston was east, while at Burling- 
ton and Portland it was south, but the velocity at all of the 
stations was so small that I have preferred to record it as a 
calm. ‘The center of this depression was on the southeast side 
of Mt. Washington. In No. 72 the winds preceding the min- 
imum pressure at several stations blew from the south, but the 
prevalent direction appeared to be S.W. This low center 
comparisons 87. 
There were 40 cases in which the change of wind from the 
west to the east quarter was felt at the base but not at the sum- 
mit of Mt. Washington, that is, 46 per cent of the whole number 
of cases ; and there were two cases in which this change occurred 
at the summit but did not occur ina decided manner at the 
base. These cases are Nos. 27 and 60. In No. 27 at 25.1 the 
wind at Burlington was south, and at Portland was northeast, 
but the prevalent direction of the surface winds in the vicinity 
of Mt. Washington appeared to be west. It will also be ob- 
served that the wind at this time on Mt. Washington was very 
