527 
of Edinburgh, Session 1868 - 69 . 
west of line of minimum barometer bore to the winds on the east, 
according to the direction of this line with respect to the meridians. 
ls£, When the minimum line is straight, or nearly so, on the 
meridians, as on morning of 18th March, the winds change from a 
southerly or easterly direction to west or north-west. This holds 
true as far to the northwards as the pressure decreases from south 
to north on the line of minimum barometer, as it did over an 
extent of the line, on the morning of 18th March, for upwards of 
800 miles. Under these conditions, a calm or lull of the wind 
occurs along the line before the wind changes suddenly to the 
west or north-west. 
2d, On the northern border of the storm, where the line of mini- 
mum barometer is curved, or lying from south-east to north-west, 
as in Scotland during “ Royal Charter” storm, the wind does not 
calm down, but veers from north-east to north and west. 
3cZ, On the southern border of the storm, when the line lies from 
north-east to south-west, as in common in the valley of the Mis- 
sissippi west of the river, the winds are more northerly there and 
along the Grulf than in any other part of the United States. When 
this direction of the line occurs in Scotland, we are liable to such 
eruptions of northerly winds as wrecked the “ Ivanhoe” in Decem- 
ber 1867. 
4:th, When the minimum line of barometer on the southern 
border of the storm lies from south-east to north-west an oppo- 
site state of things occur. The winds do not lull or veer at first; 
the cold current from the west rushes in behind the south-westerly 
warm winds, and causes the temperature to fall and the barometer 
to rise. The terminating winds on the east and west sides of the 
minimum line on the 15th and the 19th March were contrasted in 
this respect. 
The relation as well as want of conformity in contour between 
the isobarometric lines of the cold west winds and those of the 
warm southerly winds were pointed out. The phenomenon of the 
kneeing-in of the isobarometric lines on the west of the minimum 
line was exhibited. The phenomenon was parallel in principle to 
that formerly shown by the author, as existing in the south of 
England and north of France on morning of 3d December 1863. 
The author then pointed out the extraordinary different results 
3 z 
VOL. VI. 
