Observations of the United States Signal Service. 9 
Near the Atlantic coast. 
From the coast to long. 92°. | West of longitude 92°. 
| 
Station. Lat. |Cases.|| Station. Lat. |Cases.| Station. Lat. |Cases. 
Cape Rosier |48°52’| 11 | Marquette  /46°33’| 3 ||Fort Garry (49°51’} 8 
Father Point |48 31 6 ||Escanaba 45 46 2 ||Fort Benton |47 52 1 
Chatham 7 eae 2 ||Montreal 45 31 1 |\Duluth 46 48 vu 
Quebec 46 48 | 17 ||Ottawa 45 26 | 2 !/Portland, Or. |45 30 | 4 
Sydney 46 8/| 17 || Alpena 45 5} 2 ||St. Paul 4463] 1 
Eastport 44 55 9 ||Grand Haven !43 5 1 ort Sully 44 39 | 17 
alifax 11 ||Milwa’ 3{ 3 |/Yankton 42.45 | 1 
Burlington 29 | 1 ||Buffalo 42 53 1 |Omaha 4116) 3 
Portland, Me. 43 40} 9 ||Dubuque 42 30 | 2 |\Leavenworth |39 19 | 2 
B 21 | 1 ||Oswego 42 28] 1 
New London |41 22] 1 ||Keokuk 40 23 | 1 
Cape May 38 56] 1 
Norfolk 36 51 1 
Wilmington (34 11 1 
Punta Rassa |26 29 2 
We see that cases of low barometer occur most frequently at 
the northern stations, and none have occurred south of latitude 
39° except on the Atlantic coast. The cases of low barometer 
appear to be pretty uniformly distributed along the different 
meridians until we come within two hundred miles of the 
Atlantic coast, with but one exception, viz. Fort Sully. 
There is reason to suspect that in 1874 the readings of the 
barometer at this station were too low. During the first six 
months of 1874 the mean height of the barometer at this station 
was more than one-tenth of an inch below that of the neigh- 
boring stations Duluth, Breckenridge and Yankton. If we 
apply this correction to the observations reported at Fort Sully, 
the number of cases at this station below 29°25 inches will be 
reduced to four, which accords yery well with the results at 
other western stations. The observations at Cape Rosier, 
Father Point and Sydney did not commence until November, 
1873, and those at Chatham in October, 1878. There is then 
a sudden increase in the violence of storms on approaching the 
Atlantic coast, and this may be ascribed to the increased sup- 
ply of aqueous vapor coming from the ocean and the Gulf 
Stream. This increased supply of vapor results in an increas 
fall of rain ; that is, increased expansion of the air, causing an 
increased violence of the wind, and hence diminished pressure. 
In nine of the cases included in the table on page 2, the 
velocity of the wind was reported zero, and in thirty-one cases 
the velocity did not exceed five miles per hour, showing that 
near the center of an area of low pressure there is usually a 
period during which the air is almost entirely calm. mie 
Tn fifty-three of the cases included in the table, no rain was 
reported for the preceding eight hours at the station where the 
barometer was lowest; and in seventy-eight of the cases the 
