362 H. A. Hazen—Projection of Lines of Equal Pressure. 
TABLE I. 
Departures at North Platte, Neb., elevation 2838 feet, for the observation at 
4.35 
A.M. Washington time, during January, 1879. 
Pressure. Departure. 
. Date.| Temp. 
Actual. | $'8-Srv-| taPiace.| Hazen. | Actual.| 8.8. | L. H. 
1 °| 94"-22| 307-08} 307-55| 307-42 9 18 21 15 
2| —13 |. 27°27 | 30°26 | 30°74 | 30-55 14 35 40) 28 
3/—8]| 27-44] 3043 | 30°90] 30°71 31 53 5 
4} —9]| 27-31 | 30°27 | 30°71 | 30°57 18 37 37 30 
5 4| 27°41 | 30:31 | 30°65] 30°60 28 4] 31 33 
6 1| 27-01 | 29°85 | 30°30 | 30°23 19°) — —4 
7 25 | 27°03 | 29°70 | 30°35] 30°12 | —10 | —20 | —21 | —15 
8 1{| 27°26 | 30°14] 3054 | 30°45 13 24 20 
9 0!| 2698} 29°81 | 30°30] 30°19 5}|—9|—4)— 6 
10 12 | 26°97 | 29°72 | 30°18] 3012 ' —16 | —18 | —16} —J5 
11 3 | 27°15 | 29-99 | 30°49 | 30°35 : 9 15, 8 
12 6 | 27°04] 29°84] 30°32] 3023} — 4 
13 14 | 26°98 | 29°72 | 30716] 30712 | —15 | —18 | —18 | —15 
i 6} 27°05 | 29°86 | 30°31 30°2 — — 4} 48 [io < 
15 10 | 26°99 | 29°75 | 30°23 | 30715 14 | —15 | —11 | —12 
16 57-08 | 29°91 | 30°41 | 30°98 | — 5 1 
17 9} 2706 |29'85 | 30°30. 30°2 W his 6 yes — 5 
18 3 | 27-23 | 30:10 | 30°57 | 30°43 10 20 23 16 
19 8 27°32 30°18 30°56 30°49 19 28 22 22 
20 23 | 27°24 | 29°97 | 30°42 | 30°33 1 8 6 
21 16 | 26°97 | 29°70 | 30°15 | 3010 | —16 | —20 | —19 | —17 
22 37 | 26°91 | 29°50 | 29°93 | 29°95 | —22 40 | —41 | —32 
23 27 | 27°13 | 29°82 | 30°22 | 30-2 — §} —12] — 
24 36 | 26°92 | 29°51 | 29°94 | 29°96 | —21 | —39 | —40| —31 
25 37 | 27°31 | 29°98 | 30°33 | 30°34 1 - 
26 35 | 26°65 9°20 | 29°59 | 29°69 | —48 | —70 | —75 | —58 
a7 30 | 26°91 | 29°54] 30:00 | 29:97 | —22 | —36 | —34 | —30 
28 26 | 27°08 977 | 30°20] 30 ae 13 | —14] —Il 
29 15 | 27°36 | 30°18 | 30°58 | 30°50 23 28 24 23 
30 26 | 27°34 | 30°08 | 30°44 | 30°42 21 18 10 15 
31 27 | 27:27 | 29:98 | 30°37 | 30°34 1 3 7 
Mean 27°13 | 29°90 | 30°34 | 30°27 
A comparison of the “departures” shows a difference of 
+010 between columns 7 and 10, and a still greater differ- 
ence between 7 and 8 or 9. This discrepancy would be muc 
increased at greater altitudes. No satisfactory projections then 
can be made with this system. : 
Having given pressures and temperatures, we may obtain an 
approximate difference of elevation, of neighboring stations, by 
i he formula of LaPlace. In order to obtain som 
idea of the accuracy of leveling with the barometer the differ- 
ence of height of the following stations has been computed, 
see Table I. 
