E. Loomis— Observations of the U. 8. Sighal Service. 17 
The average of the greatest velocities for the southwest quar- 
ter is 23 miles per hour, and for the northeast quarter it is 29 
miles per hour. There are several instances in which the mode 
of comparison here adopted does not fairly indicate the relative 
force of the winds on the opposite sides of a low center, espe- 
cially when the low center happens to be situated near the 
margin of the Signal Service map, but the average of the results 
when the storms were advancing towards the northwest, and 
also when they were advancing towards the southwest, appears 
very decided, and seems to indicate distinctly that the centers 
of least pressure advanced in that Hosoda towards which the 
winds pressed in with the greatest fo 
n my first paper I gave the result a ‘two years’ observations, 
which showed that the ae velocity of the wind on the 
west side of a low center (within the isobar 29°90) was 10-1 
miles, and on the east side 8°38 miles; being 22 per.cent greater 
on the west side than on the east side. We have now found 
that when a low center advances westward, the velocity of the 
wind is generally - Nahe on the east side of the low center. 
The progressive movement of storms probably depends upon 
- meteorological ie es which prevail at a considerable dis- 
tance from the low center. oe charts and the Inter- 
national maps sometimes inform us w these conditions are. 
The following summary shows certain poi etins which pre- 
vailed at each of the cases contained in the table on Lanes 15, as 
far as is shown by the maps which I have receiv 
No. 3. High on the north and east (765) with low (735) near South Greenland. 
No. 4. High on = northeast (775 to 785) with low (735) near Newfoundland. 
No. 5. High on the east (770) with low (740) near Iceland. 
r High on the northeast (775) with low (7 nih ied the Atla: 
No. 9. High on the east (30°20) with low (29°20) near a ewes 
No. 10. High on the northeast (30°60) with low (29°40) over ox ae tlanti 
id Pes High on the north and northeast (30°20) with low (29°00) over “N orth- 
No. 12. High on the north and northeast (30°20) with low (29°40) near South 
Greenland. 
No. 13. High on the north and east (30°20 to 30°40) with low (29°60) near 
Iceland. 
Thus we see that in the preceding cases there generally pre- 
vailed a considerable area of low pressure over the Atlantic 
cean, while on its western or northwestern side a cold wind 
from the north, with high pressure, was forcing its way south- 
ward, and this. may be presumed to have crowded westward 
e low areas prevailing at the same time over the United 
tat 
ollowing summary presents some of the conditions 
prevailing at these dates on the id eneice side of these low 
reas. 
Am. Jour, oe Series, VoL. XXI, No. nee 1881. 
