: eo —? Mountains and two on the east 
4 E. Loomis— Observations of the U. S. Signal Service. 
_ In each case the center of low pressure traveled eastward, 
and can be traced to the Atlantic coast. No. 11, being a 
depressed period of five days’ continuance, should probably be 
regarded as consisting of two abt bene areas, the second of 
which immediately succeeded the first, so that the two were 
united in Oregon, but traveled across the continent indepen- 
dently, one of them reaching the Atlantic four days later than 
the other. So also No. 12 apparently consisted of two depressed 
areas which were united in Oregon, but traveled across the 
continent ‘skeet one of them two days later than the 
other. average time of crossing the continent was five 
days, and the average latitude where the low center met the 
Atlantic was 45°. 
he paths by which these areas of low pressure crossed = 
continent differed considerably from ares of great circles. Sta 
ing from the Pacific Ocean, generally as far north as jatitdle 
50°, the course was toward the southeast, until near the middle 
of the continent, and on the scsi dines of 100° from Greenwich 
the average latitude of the paths was 40°. Thence the course 
radually veered northward, and upon reaching the Atlantic 
the average latitude of the paths was 45°. 
Low barometer at San Francisco, California. 
The observations made at San Francisco have been discussed 
in the same manner as those = Portland. The following table 
shows all the cases in which (during a Peres of twenty-six 
months) the Barcieier fell as low as 29-7 inches. The tabl 
constructed in the same manner as that for Portland. 
The number of these cases is twenty-nine, corresponding to 
nine different storms, and most of them occurred during the 
winter months. A single case is reported for the summer 
months, which b apparently resulted from causes operating over 
the central of the North American continent. 
fourths of the cases the wind blew from some southern quarter, 
and in only three cases did it blow from a northern quarter. 
e average velocity of the wind was fifty per cent greater 
than at Portland, a ace which may be ascribed to greater 
proximity to the oc 
more than jaca of the cases the pressure at San Fran- 
cisco was the lowest reported at any station at the same hour. 
In eleven of the cases the greatest depression was on the east 
side of the Rocky Mountains, and in eight cases the point of 
reatest depression was situated about 1400 miles eastward. 
Five of these depressions appear to cae originated over the 
Pacific Ocean; the remaining four appear to have originated 
north of the United States, two of them — the west side of the 
o: ta i id 
