20 



still more to 29. 5G inches. In the mean time an area of high pressure 

 developed at Dodge City, Kans. The effect on the wind was as fol- 

 lows : From Saint Louis southward the winds began to shift to SW.; to 

 the northwest of that place they became NW. and ~N.; while to the 

 northeast of Saint Louis they shifted to SW. and W. As would be 

 expected, those places which had W. and NW, winds had clear skies, 

 while the district from Saint Paul and La Crosse to Chicago and east- 

 ward was cloudy. The temperature from Saint Paul northwest, north, 

 and northeast rose. At Saint Paul it was stationary, and thence south- 

 ward it fell a few degrees, but still remained warm. The wave of migra- 

 tion seems to have exhausted itself in a single night. Some forty 

 'firsts' were recorded for this day, but, except at two places, they 

 seem to have been arrivals of the previous day, which had been over- 

 looked. These two stations, Waupaca, Wis., and Heron Lake, Minn. 

 (with its neighborhood), furnished one-half of the forty records, and 

 both are on the northern edge of the district covered by the preceding 

 night's migration. It seems, then, that at these places there was a local, 

 though, in the case of Heron Lake, a very large migration. 



March 24 was marked by cloudy weather after a clear night. South- 

 erly winds prevailed over the Upper Mississippi Valley, varying from 

 SE. to SW., and mostly light. The temperature had fallen, on an av- 

 erage, 5° from Chicago to Bismarck and northward. It had risen 

 strongly 9° to 11° at Yankton and Omaha, this rise probably being the 

 cause of the arrival of immense numbers of water-fowl during the day 

 at Heron Lake, Minn., all coming from the west, that is, from the 

 direction of Yankton, at which place at 7 a. m. a S. wind was blowing. 

 It was a day of general low pressure. The whole district, from Cairo 

 to Moorheacl, was included between 29.80 and 29.89 inches. Northward 

 and eastward, iu Manitoba and at Marquette, Mich., the barometer fell 

 to 29.65; in the southwest, at Fort Smith, Ark., it fell to 29.71; and 

 westward, at Dead wood, Dak., it rose to 30. An area of low pressure 

 developed at Fort Smith, Ark., in the early evening of March 23, and 

 became pronounced during the next twenty-four hours. At 7 a. m. of 

 the 24th the effect of this area was hardly felt, but by night the wind 

 had been attracted to it over most of the Upper Mississippi Valle} r , 

 bringing from the north colder, clearer weather. This day, therefore, 

 was the turning point, and the beginning of a cold wave which was 

 already felt to the northwestward of Cheyenne. The temperature at 

 11 p. m., March 21, was 47° at Saint Louis, 42° at Chicago, 50° at Des 

 Moines, 37° at Saint Paul, and 32° at Moorhead. 



This was the last day of the warm wave which commenced on the 

 evening of March 21, and the birds made the most of their opportunity 

 and advanced a whole degree farther north. The hosts which had 

 rested during the night of the 22d moved forward and fully occupied 

 all the country up to latitude 45°, with an innumerable host along the 

 Mississippi Eiver at 45° 25', and scouts up even to 47° on the Mis- 

 souri. 



