CHAPTER IX. 
Meteorological Observations, and Tables of Altitudes and Distances. 
I.—Introduction to meteorological table and "ie of altitudes and distances, on the line of the forty-first parallel of north 
latitude, explored for the Pacific railwa: 
II.—Meteorological table at Great Salt Lake City during the winter of 1853-54. 
III.—Summary of ee E observations at Great Salt Lake City in 1853 E 1854, in mean results at each observed 
hour for the several months; barometric reading corrected for temperatur 
IV.—Barometric means for map vicis observed at Great Salt Lake City, 150-94 from all the observations, including 
those at irregular hours, and corrected in detail fur horary variation of pressu 
V.—Meteorolegical observations and table of altitudes and distances from Great gal Lake City to Green " id 1854. 
VI.—Data for profile from Smith's fork, Green River valley, to that of Great Salt Lake, via the Timpanogos 
VII.—Data for Secum from Great Salt Lake valley, via the Weber river, to White Clay ereek, the Mida Bur; being in 
n with this from the latter point eastw 
VII. fomes al observations v» table of Miis from Great Salt Lake City, Utah Territory, to the valley of the 
ogic 
acramento river, California, 1854. 
IX.—Meteorological observations ae table of det from Mud lake, via Mud creek, to the summit of the Sierra Nevada 
elin Pass. (Table not used in pro 
bir —Continuation of Tab 
eteorological benes and table of altitudes in crossing from Madelin to Noble’s Pass, on the summit of the 
ra Nevada. (This table is not used in profile. 
Sier: 
VIII.—Table VIII again resumed. 
XL— pire rs observations and table x altitudes and distances for profile from Mud lake to Fort Reading on the Sac- 
ram 
iver, California, via Noble's 
Laser us observations and table ei 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 thegce west to Hat and Wolf creeks. (This table is not used in profile.) 
I.—Jntroduction to meteorological table and table of altitudes and distances on the line of the forty- 
Jirst 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 bee 
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 indic 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 
