A stone “bench” or monument for permanent reference has also been placed on rising ground near the observation pillar, and the two will be connected by spirit level. The Farmington bench is of gneiss, and is marked with a + in the same manner as the Black Rock. The stone was contributed by Mr. Abbott, of Farmington, and was gratuitously shaped and placed by Mr. Miller.
Mr. Miller has also voluntarily assumed charge of the record, and will make or superintend the observations. It will not be practicable to visit the pillar daily, nor even at regular intervals, but it is expected that the record will be as full as the one tabulated above. The following items are to be noted:
1. Time of observation, including year, month, day, and hour.
2. Reading of water surface in feet and inches.
3. Direction and force of wind.
4. Account of wind for the preceding 24 hours.
5. Name of observer.
These observations will not only determine the annual gain or loss of the lake, but will in a few years give data to construct the curve of the annual tide.
The history of past changes not having been the subject of record, it became necessary to compile it from such collateral data as were attainable. The enquiries inaugurated by Professor Henry have been prosecuted, and have resulted in a tolerably definite determination of the principal changes since 1847, together with the indication of a superior limit to earlier oscillations.
Ever since the settlement of Salt Lake City, in 1847, the islands of the lake have been used as herd grounds. Fremont and Carrington islands have been reached by boat, and Antelope and Stansbury islands partly by boat, partly by fording, and partly by land communication. A large share of the navigation has been performed by citizens of Farmington, and the shore is in that neighborhood so flat that the changes of water level have necessitated frequent changes of landing place. The pursuits of the boatmen have been so greatly affected that all of the more important fluctuations were impressed upon their memories, and most of the changes were so associated with features of the topography that some estimate of their quantitative values could be made. The data which became thus available were collated for Professor Henry by Mr. Miller, a gentleman who himself took part in the navigation, and of whom I have already had occasion to speak. His results agree very closely with those derived from an independent investigation of my own, to which I will now proceed.