Summary Narrative of an Exploratory Expedition to the Sources of the Mississippi River, in 1820 / Resumed and Completed, by the Discovery of its Origin in Itasca Lake, in 1832 - Henry Rowe Schoolcraft

Temperature of Lake Superior.
				Lake average.
June 20, at 6 P.M., 55°
" 21, at 10 A.M., 60	at 6 P.M., 56°	at 9 P.M., 56°		57
" 22, at 6 A.M., 56	at 3 P.M., 54			55
" 23, at 5 A.M., 52	at 12 A.M., 56	at 10 P.M., 64		57
" 24, at 6 P.M. 54	at 7 P.M., 51			53
" 25, at 7 A.M., 67	at 11 A.M. 66,	at 9 P.M., 68		60
" 26, at 9 A.M.,	56 at 8 P.M., 57			56
" 27, at 8 A.M., 57	at 6 P.M., 62			60
" 28, at 8 A.M.,
Superior 62° at 6 P.M.,Lake 72 Ontonagon 54River 71				}67
" 29, at 8 A.M.,				61
Lake 64 River 68 at 1 P.M., River 76 at 7 P.M., 75°
" 30, at 8 P.M.,
River 74
July 1, at 8 A.M., 61	at 2 P.M., 65	at 6 P.M., 66		64
" 2, at 4 A.M., 63	at 11 A.M., 64	at 2 P.M., 68	at 9 P.M., 62	64
" 3, at 6 A.M., 62	at 3 P.M., 60	at 9 P.M., 58		60
" 4, at 7 A.M., 58

Superior 62°
at 6 P.M.,Lake 72
Ontonagon 54River 71

Lake 64
River 68
at 1 P.M., River 76
at 7 P.M., 75°

River 74

It will be observed that the fluctuations of temperature noticed at lower points on the lake chain, about the latitude of Michilimackinac, have also characterized the entire length of Lake Superior. The atmosphere observed at three separate times, during twenty-four days, by Fahrenheit's thermometer, during the months of June and July, has varied from an average temperature of 62° to 88°, agreeable to masses of clouds interposed to the rays of the sun, and to shifting currents of wind, which have often suddenly intervened. Its waters, spreading for a length of five hundred miles from E. to W., observed during the same time by as many immersions of the instrument, has not varied more than two degrees below or above the average temperature of 55° in mere surface observations.

Observations on the Sources of the Mississippi River.
	5 A. M.	7 A. M.	8 A. M.	12 P. M.	2 P. M.	8 P. M.	9 P. M.	REMARKS.
July 17	...	...	...	76°	80°	79°	78°	Morning rainy, then fair.
" 18	...	...	51°	64	66	53	50	Fair.
" 19	...	...	46	63	70	55	...	Night rainy, morning cloudy, then fair.
"; 20	...	...	60	80	84	75	...
" 21	...	...	68	86	88	85	74
" 22	...	...	73	88	90	77	...	Cloudy, some thunder.
" 23	...	...	70	82	88	78	...	Night and morning rain, afternoon thunder.
" 24	...	...	74	87	80	78	...	Fair.
" 25	...	...	...	...	85	74	...	Fair.
" 26	61°	...	...	...	81	61	...	Morning fair, evening cloudy and rain, clear.
" 27	62	...	...	...	80	75	...	Morning fair, evening fair.
" 28	62	...	...	...	76	61	...	Morning fair, rain in afternoon.
" 29	50	...	...	...	74	52	...	Clear.
" 30	...	60°	...	...	76	...	63	Wind N. W., weather clear.
" 31	...	65	...	...	81	...	69	Wind W., weather clear.
Aug. 1	...	67	...	...	83	70	...	Fair.
" 2	...	72	...	...	[ [263]	...	...	Fair.

Observations at St. Peter's (now Minnesota).
1820.	7 A. M.	2 P. M.	9 A. M.	WINDS.	WEATHER.
July 15,	61°	79°	64°	S.	Clear; fair.
" 16,	62	82	76	S.	Clear; rain towards morning.
" 17,	70	88	61	W.	Cloudy; rain, thunder and lightning.
" 18,	58	78	56	E.	Clear.
" 19,	59	80	64	S.	Cloudy; rain P.M.
" 20,	68	80	65	S.	Clear.
" 21,	69	84	72	S.	Clear.
" 22,	75	88	72	W.	Clear; cloudy P.M., rain, thunder and lightning during the night.
" 23,	73	86	70	W.	Clear, cloudy; rain and fair weather alternately.
" 24,	70	89	72	W.	Clear; calms.
" 25,	70	80	66	W.	Clear; high winds at night.
" 26,	68	82	64	W.	Clear; calm.
" 27,	72	78	62	W.	Clear.
" 28,	67	75	58	S. E.	Clear; fresh winds.
" 29,	60	71	54	N. E.	Clear.
" 30,	60	76	63	N. W.	Clear.
" 31,	65	81	69	W.	Clear.

Meteorological Journal kept at Chicago by Dr. A. Wolcott.
1820.	Daylight.	9 A. M.	2 P. M.	9 P. M.	WIND.	WEATHER.
Jan. 1,	4°	11°	10°	0°	W. N. W.	Cloudy; light snow; first ice in the river, 14 inches thick; none in the lake.
"2,	10	14	25	12	W. N. W.	Clear.
"3,	4	9	13	14	W. S. W.	Clear.
"4,	9	14	19	9	W.	Clear.
"5,	9	5	4	10	W. N. W.	Clear.
"6,	11	4	15	28	S. S. W.	Clear.
"7,	36	36	39	36	S. W.	Cloudy.
"8,	32	32	34	33	N. N. E.	Cloudy.
"9,	32	33	36	34	N. E.	Cloudy.
"10,	32	31	31	25	N. E.	Snow-storm.
"11,	14	14	16	2	N.	Clear.
"12,	17	15	2	12	S. S. W.	Clear.
"13,	20	24	25	12	W. S. W.	Clear.
"14,	14	15	15	15	N.	Snow-squalls.
"15,	12	14	15	10	N. N. W.	Clear; lake covered with moving ice, as far as the eye can see.
"16,	20	20	21	21	E. N. E.	Snow-storm.
"17,	14	14	25	10	W. N. W.	Clear.
"18,	14	18	15	6	W.	Cloudy.
"19,	10	0	10	2	W. N. W.	Clear.
"20,	6	12	25	13	W.	Clear.
"21,	20	22	26	28	E. N. E.	Snow-storm.
"22,	7	11	12	5	N. W.	Clear.
"23,	20	4	0	3	W.	Clear.
"24,	2	6	18	16	W.	Clear.
"25,	4	3	9	7	W.	Clear.
"26,	16	19	26	28	E. S. E.	Snow-storm.
"27,	18	21	25	8	S. W.	Cloudy.
"28,	8	1	11	10	W. N. W.	Clear.
"29,	12	20	31	18	W.	Cloudy; ice 18 inches on river.
"30,	6	6	4	5	W.	Clear.
"31,	6	5	3	17	W. N. W.	Clear; snow 22 inches deep.
Feb. 1,	12	0	14	16	S. E.	Cloudy.
"2,	22	25	29	20	E. N. E.	Snow-storm; ice 18¾ inches on river.
"3,	10	7	9	7	W.	Clear.
"4,	0	5	25	24	E. S. E.	Clear.
"5,	30	36	40	40	S. W.	Clear.
"6,	11	12	32	24	S.	Clear.
"7,	28	33	42	30	W. S. W.	Clear.
"8,	30	34	40	32	E.	Cloudy and mist; snow during the night fell six inches.
"9,	30	34	34	31	E.	Clear.
"10,	31	32	39	32	E.	Cloudy.
"11,	28	32	38	34	S.	Clear.
"12,	32	39	34	20	N. E.	Cloudy.
"13,	12	22	39	32	W. S. W.	Clear.
"14,	34	39	37	36	E.	Cloudy; some rain with thunder.
"15,	36	38	39	36	E.	Cloudy; some rain with thunder.
"16,	38	42	47	33	S. W.	Clear.
"17,	27	27	28	22	W.	Light clouds.
"18,	10	22	28	30	E.	Cloudy.
"19,	32	36	46	24	W.	Clear.
"20,	15	22	24	16	W.	Clear.
"21,	8	20	37	38	S. W.	Clear.
"22,	34	40	45	32	W.	Clear.
"23,	28	37	46	36	S. W.	Cloudy; rain and hail with thunder.
"24,	30	33	40	39	E.	Clear.
"25,	44	50	59	54	S. W.	Clear.
"26,	50	49	38	36	S. W.	Cloudy; tempest of wind with flurries of rain and hail.
"27,	30	31	34	28	W. N. W.	Clear.
"28,	20	28	30	39	S. E.	Clear.
"29,	28	36	50	37	S. W.	Clear.
Mar. 1,	32	35	36	18	N. N. W.	Clear.
"2,	8	15	25	20	N. N. W.	Clear.
"3,	26	30	36	22	W. N. W.	Cloudy.
"4,	19	28	42	36	S. W.	Clear.
"5,	30	32	36	23	N. E.	Cloudy.
"6,	13	19	25	14	N. N. W.	Clear.
"7,	16	17	24	18	E. N. E.	Cloudy; light snow.
"8,	17	24	23	21	N. E.	Cloudy.
"9,	22	24	26	23	N. N. E.	Cloudy.
"10,	24	26	31	24	N. N. E.	Cloudy.
"11,	22	24	29	31	E. N. E.	Cloudy.
"12,	28	32	33	32	E. S. E.	Cloudy; light snow.
"13,	32	37	39	34	E. N. E.	Cloudy.
"14,	32	36	36	33	E. N. E.	Cloudy; light snow.
"15,	26	32	...	...