BAROMETRICAL AND METEOROLOGICAL OBSERVATION'S. 207 



Independence Rock. (Sweetwater River,) August 16th, 3p.m., 91 and 59 .3; 

 difference, 31°. 7 Fahrenheit 



Camp Floyd, September 17th, 3 p. m., 90° and 54 - : difference, 36 Fahrenheit 



Prince's Creek, Utah, August 2d, 3 p. m., 87°.5 and 56°; difference, 31 .5 Fahren- 

 heit 



In that vicinity, and about that time, the difference reached frequently 30°. At 

 Genoa, Carson Vallev, June 16th, 88°.5 and 56°; difference, 32°.5; and for several 

 hours, 30 or 31°. At the same place, June 17th, 2 p. m., 92° and 58°.5: difference, 

 33°.5; and for several hours, 32°. On June 18th, 1 p. m, 94° and 59°; difference, 

 35°. June 19th, 12 m., 90° and 56°; difference, 34°; and June 20th, 3 p. m., 101 .5 

 and 66°; difference, 35°.5 Fahrenheit. 



The force of vapor is subject to rapid changes by a change of the wind, and from 

 other apparently small causes, independent of the regular daily variations. We find 

 a change recorded on Big Sandy Creek, near Green River, August 2<th, from (..20 

 p.m. to 9 p.m., from 0.176 to 0.415: difference, o.l>0!) inch; and at Genoa, June 

 16th, from 12 m. to 1p.m., from 0.204 to 0.088; difference, 0.116 inch in 1 hour, 

 merely by a change of the wind, with a perfectly clear sky; and at the same place, 

 on June 19th, from 11 a. m. to 12 m., from ...252 to O.067 : difference, 0.185 inch in 

 1 hour. Some of the lowest values of force of vapor were deduced from observations 

 at the following points: Copperas Springs, near Fort Bridger, September 27th, to 6 

 p. m., 0.000; Salt Lake Desert, May 8th, 9 p. m., O.nOO; Pleasant Valley, Utah, May 

 9th, 3 p. m., 0.028 ; Antelope Valley, May 10th, 12 in., 0.027; Camp Floyd, April 21st, 

 5 p. m., 0.008 ; Camp Floyd, September 17th, 3 p. m., 0.014; Camp Floyd, January 

 12th, 7 a. m., 0.025, when the air was saturated with moisture on account of the low 

 temperature; also, January 11th, 7*. m., 0.026; January 10th, 9 p. in., 0.026; Fort 

 Bridger, September 4th, 3.30 p. m., 0.027 ; Fort Bridger, September 29th, 10 a., m., 

 0.022 ; Woodruff Valley, May 31st, 6 p. m., 0.015. 



Extremely small values of saturation, or relative liumidity, arc the following : Cop- 

 peras Springs, near Fort Bridger, September 27th, 6 p. m., 0; Salt Lake Desert, May 

 8th, 9 p. m., ; and at neighboring points, on successive days, 4 and 7 ; Fort Bridger, 

 September 4th, 3.30 p. m., 3; Fort Bridger, September 29th, 10 a. m., 3; Camp Floyd, 

 April 21st, 5 p. m., 2; April 23d, 6 p. m. and 8 p. m., 11; Camp Floyd, August 8th, 

 4 p. m., 9; Prince's Creek, August 2d, 3 p. m. and 6 p. m., 8; Woodruff Valley. May 

 30th and 31st, 6 p.m., 3; June 1st, 3 p. m., 3; Alkali Wells, June 4th, 6 p.m., 7; Walker 

 River, June 8th, 3 p. m., 7; Genoa, June 19th, 12 m., 5: Little Sandy Creek, near South 

 Pass, August 26th, 3 p. m., 8; and as tar east as Fort Kearney, October 3d, 3 p. m., 10.5. 



It was astonishing to see how little influence, sometimes, rain had on the humidity 

 of the atmosphere, because it was found in the upper regions while the lower atmos- 

 phere was dry, and it did not extend far. At Plympton Springs, in the Salt Lake 

 Desert, July 23d, between 3 and 4 p. m., 0.30 inch of rain fell, during a thunder- 

 storm, with hail ; our camp was flooded, and after 6 some more rain fell. Still the 

 relative humidity, which at 3 p. m. was 38, at 6 p. m. had only increased to 50. 

 Ao-ain, in White Valley, on July 25th, a thunder-storm, with, however, only little rain, 

 was recorded as lasting from 4 to 6 p. m.; the relative humidity at 4 p. m. was 25; at 6 

 p. m., 28. 



