J. W. Powell's Survey of the Rocky Mountain Region. 849 
the water supply has increased. It is reported by the citizens 
that each stream is now capable of irrigating a greater area of 
land than when it was first used. Creeks that once scan- 
tily watered a few acres of ground now afford an ample supply 
or double, treble, and even fifty times the original area. This 
increase has been accompanied by a rise of Great Salt Lake, 
which having no escape for its water except by evaporation 
has stored up the surplus from the streams. 
or the purpose of investigating the extent and the cause of 
the increase of the streams, Mr. Gilbert made a study of the 
fluctuations of the lake. It was a matter of common report 
that the surface of the water had been subject to considerable 
changes and that on the whole it bad greatly risen since its 
shores were first settled; but previous to the year 1875 no sys- 
tematic record of its movements had been kept. In that year 
a series of observations was inaugurated by Dr. John R. Park 
of Salt Lake City, at the suggestion and request of the Secre- 
tary of the Smithsonian Institution. A small pillar of granite, 
graduated to feet and inches, was erected at the water's edge 
near a rocky islet known as Black Rock. The locality was then 
a popular pleasure resort, and the record was undertaken by 
r. J. T. Mitchell. Observations were made at frequent inter- 
vals for more than a year, but were then interrupted by reason 
of the disuse of the locality as a place of resort, and they have 
not since been resumed in a systematic way. To obviate a 
similar difficulty in the future, Mr. Gilbert caused a new record 
post to be established near the town of Farmington, where the 
work of observation has been undertaken by Mr. Jacob Miller, 
and it is anticipated that in the future there will be no break in 
the continuity of the record. ; 3 
In the interval from 1847 to 1875, during which no direct 
observations were made, there was nevertheless a considerable 
amount of indirect observation incidental to the pursuits of the 
citizens. The islands of the lake were used for pasturage, 
testimony of the boatmen was compiled by Mr. Jacob Miller 
and a history of the oscillations was deduced. 
A similar and corroborative history has been derived by Mr. 
Gilbert from an independent investigation. Two of the islands 
used for pasturage are joined to the main Jand by broad, flat 
bars, and during the lower stages of the lake these bars being 
