United Slates Weather Maps and other sources. 13 



other term of the formulas varies as the square of the sine of 

 the latitude, and this law of increase holds pretty closely up to 

 about latitude Qb''. That part of the barometric oscillation 

 represented by the first term of the formula is the effect of 

 storms, and the oscillation diminishes within the Arctic circle. 

 These results seem to indicate that in the Northern Ilemis- 

 phere, storms increase in frequency as we proceed northward as 

 far as latitude 60° and perhaps somewhat farther. The same 

 result is shown by Maury's storm chart of the North Atlantic. 

 The preceding table presents a summary of the results of this 

 chart. The ocean is divided into squares by parallels of lati- 

 tude drawn at intervals of five degrees from eacb other, and 

 meridians of longitude at intervals of five degrees Each 

 square of the preceding table contains three numbers. The first 

 shows the number of observations within the given square, 

 each observation representing a period of eight hours. Tiie 

 second shows the number of gales reported, and the third is 

 the average number of gales occurring in'a hundred observa- 

 tions. Thus in the square included between the parallels of 

 40° and 45° of north latitude, aiid between the meridians of 

 45° and 50° west longitude from Grreenwich, the first number 

 is 1863, which shows the number of observations obtained in 

 that square. The second number is 280, which denotes the 

 number of gales reported; the third number is 15, which de- 

 notes that the number of gales was 15 per cent of the whole 

 number of observations. An inspection of this table will 

 show that on each meridian the frequency of gales increases 

 with the latitude up to the highest latitude from which obser- 

 vations are reported. 



Storms traced across the Atlantic Ocean. 

 When storms from the American continent enter upon the 

 Atlantic Ocean they generally undergo important changes in a 

 few days and are frequently merged in other storms wliich ap- 

 pear to originate over the ocean, so that we can seldom identify 

 a storm in its course entirely across the Atlantic. The follow- 

 ing are the only cases I have found on the French and Danish 

 charts (embracing a period of 27 months) in which storms can 

 be pretty distinctlv traced across the Atlantic. 



1. Nov. 30— Dec. 11, 1864. A storm traced from New- 

 foundland to Ireland. 



2. April 20 — May 3, 1865, traced from Labrador to Ireland. 



3. May 26—29, 1865, from Gulf St. Lawrence to Ireland. 



4. Oct. 2—10, 1865, from Cape Cod to Ireland. 



5. Oct. 11-17, 1865, from Newfoundland to Ireland. 



6. March 1—5, 1874, from Hudson Bav to North Cape. 



7. April 14—17, 1874, from Hudson Bay to Norway. 



