TABLE OF BAROMETRICAL MEASUREMENTS. . I9 
a different state of things; so that one's views and opinions of this country depend entirely 
upon the season during which he visits it. 
Whether water can be obtained on these plains by digging within reasonable limits, is a 
question purely problematical, to be solved in every case by experiment, owing to the geological 
structure of the country. This experiment I consider worthy of attention, not only on account 
of its great and all-important bearing upon the question of locating a thè for railroad over 
this country, where are intervals of fifty and seventy miles between permanent waters, but 
also, if successful, on account of the relief rendered the various parties crossing during the dry 
season, whose sole and great anxiety now is, when entering upon these jornadas, to get their 
animals through to the next water. 
Before closing this report, I take great pleasure in expressing my thanks for the many kind 
offices and valuable assistance rendered throughout the trip by Lieutenant George Stoneman, 
Ist dragoons, and commanding escort, an officer full of expedients and experience, the results 
of eight years’ campaigning; also to Dr. A. L. Heermann, physician and naturalist, and to 
Mr. Henry Custer, assistant; both of whom displayed a proficiency in their professions only 
equalled by the zeal bestowed upon the discharge of their respective duties. 
I have the honor to be, very respectfully, your obedient servant, 
JNO. G. PARKE, 
Lieutenant Corps Topographical Engineers. 
Hon. JEFFERSON Davis, 
Secretary of War. 
TABLE OF BAROMETRICAL MEASUREMENTS, WITH THE REDUCED APPROXIMATE ALTITUDES. 
First column of heights.—Those entered in this column were obtained by referring the prin- 
cipal camps to each other, and the intermediate stations to the nearest well-determined camp. 
The barometric reading was first reduced to 32°. After which, a correction was applied, on 
account of hourly variation, taken from the following table, prepared by L. Blodget, Esq., of 
the Smithsonian Institution, after a careful and close investigation of hourly observations made 
during the survey of the Mexican boundary; and that of Lieutenant Whipple, topographical 
engineers, in corresponding longitudes and neighboring latitudes. 
6.54 JL ds j : —.010 
1a.m a -—.040 
8 a. m —.045 
9 a.m. —.050 
10 a. m. —. 057 
11 a. m —.070 
I3. odere —.032 
1p.m +.009 
2 p.m +.030 
3 p.m +.040 
4p. m +.050 
5 p. m +.045 
6 p. m +.035 
7 p.m +.025 
8 p. m +.010 
9p. m +.005 
Second column of heights—Contains the elevations obtained by referring each observation to 
the sea-level; barometer assumed to be 30.050; thermometer, 64°. The barometer was cor- 
rected for temperature and horary variation, as in column Ist. 
