CHAPTER IX. 
Meteorological Observations, and Tables of Altitudes and Distances. 
I.—Introduction to meteorological table and table of altitudes and distances, on the line of the forty-first parallel of north 
latitude, explored for the Pacific railway. 
II.—Meteorological table at Great Salt Lake City during the winter of 1853-’54. 
III. —Summary of meteorological observations at Great Salt Lake City in 1853 and 1854, in mean results at each observed 
hour for the several mouths; barometric reading corrected for temperature. 
IV. —Barometric means for the months observed at Gr'eat Salt Lake City, 1853-’54, from all the observations, including 
those at irregular hours, and corrected in detail for horary variation of pressure. 
V.—Meteorological observations and table of altitudes and distances from Great Salt Lake City to Green river, April, 1854. 
VI.—Data for profile from Smith’s fork, Green River valley, to that of Great Salt Lake, via the Timpanogos river. 
VII.—Data for profile from Great Salt Lake valley, via the Weber river, to White Clay creek, the preceding profile being in 
common with this from the latter point eastward. 
VIII.—Meteorological observations and table of distances from Great Salt Lake City, Utah Territory, to the valley of the 
Sacramento river, California, 1854. 
IX.—Meteorological observations and table of altitudes from Mud lake, via Mud creek, to the summit of the Sierra Nevada 
and to Madelin Pass. (Table not used in profile.) 
VIII.—Continuation of Table VIII. 
X.—Meteorological observations and table of altitudes in crossing from Madelin to Noble’s Pass, on the summit of the 
Sierra Nevada. (This table is not used in profile.) 
VIII.'—Table VIII again resumed. 
XI.—Meteorological observations and table of altitudes and distances for profile from Mud lake to Fort Reading on the Sac¬ 
ramento river, California, via Noble’s Pass. 
XII.—Meteorological observations and table of altitudes on the road leading through Noble’s Pass. 
XIII.—Meteorological observations and table of altitudes in crossing from the mouth of Canoe creek (Poinsett river) to Black 
Butte creek, and thence west to Hat and Wolf creeks. (This table is not used in profile.) 
I .—Introduction to meteorological table and table of altitudes and distances on the line of the forty- 
first parallel of north latitude , explored for the Pacific railway. 
The Bunten barometers Nos. 496 and 551 are exclusively relied upon for the determination 
of altitudes of the entire line. The readings of the Aneroid barometers exhibit variable errors; 
and as the mercurial barometers retain their reliable and uniform character throughout, no 
necessity exists for the use of the Aneroids. The. zero errors found by Dr. Engelmann in his 
comparison at St. Louis, to apply to the Bunten barometers before the commencement of the 
work, did not remain as between the two instruments, even at the first considerable camps of 
the survey; they were therefore rejected in all the computations, and no zero error was at any 
time applied. For mean readings the two barometers usually agreed very nearly, the differ¬ 
ence between them being, that No. 496 was too slow in its movement when considerable changes 
of altitude occurred, and required a correction or substitution of the other in such cases. For 
mean readings at stations where several observations were taken, the results of both are believed 
to be a very near approximation to standard accuracy, and the instruments appear to have been 
but slightly, if at all deranged at the termination of the survey. The zero errors found in 
them by Dr. Engelmann, on their return, were obviously introduced after the close .of the work, 
and are therefore not applied to it. 
In the discussion of the observations, the readings were first corrected for temperature to the 
height of the mercurial column, at 32° Fahrenheit. A minor error of non-adaptation of the 
common formula to the temperature expansion determined by Shumacher for barometers of this 
