THE MISSOURI AND PLATTE RIVERS, ETO. Al 
of corrections are “large, but they are clearly within a determined 
range shown to exist at Fort Pierre by these observation 
‘These corrections are applied in all the computations of altitude, as 
well as correction for the non-periodic Met inion obtained by compari- 
son with the barometric observations made by the United States medi- 
cal department at Forts Snelling ie ee and Leavenworth. 
. It will be seen that I place the altitude (1,504) of Fort Pierre 
z ane the same as that given by Nicollet, Fort Kearny (360 feet) be- 
low that given by Captain Stansbury, and Fort Laramie (269) below 
that given by him. After careful examination of my own observa- 
tions, "Tam constrained thus to differ. 
Mr. J. Hudson Snowden made nearly all the calculations, and de- 
duced the results given in the tables, and Mr. Lorin Blodget yes 
me in the preparation and arrangement of this portion of the wo 
NOTES ON THE WEATHER. 
Saturday, June 15.—Left Fort Leavenworth; wind to-day south, 5. 
June 16.—Wind south, 7; cumulus clouds thick in the north. at 
et. 
June 17.---Overcast; raining a little occasionally in the morning ; 
wind light; clear and. hot n the afternoo n; in the evening cumulus 
clouds oecupied the horizon rates north around by west to south, and 
at 9 o'clock there were continual flashes of lightning; about 12 0’ “clock 
> a most aoe storm of wind, rain, lightning, and thunder came upon 
us from the west, and lasted for an hour. oe 
June 18. —Clear most of the day Gia warm; at dark pegesiner threat- 
ening storm appeared in the west, but did not reach u 
June 19. —Very warm. 
June 20.—Very warm; at sunset another violent thunder hades 
came from the NW.; rained during the nig 
June 21.—Clear and cool; wind Ji ght NW.; was able to see the 
15th. 
e 22.—Clear and cool; thermometer at noon 74°; at midnight 
une 23 and 24.—Fai 
dune 25. —Near the Eanath of the Vermilion eee wind SW., 7, 
during the day ; thermometer at noon 873°, we ulb 7 24; at sunset 
dark cumulus clouds came from the sieickhs eee = the time blowing 
e from the south; at 9 p.m. Tatbomibter 28; attached thermometer 
ike Aiecked 14; raining heavy to ae north, rie a storm passing 
: south of us moving to the SE., wind n r 8. The flashes 
view of this commotion of the elements pociais us. 
June 26,—Clear and nearly calm. 
