274 GEOGRAPHIC TABLES AND FORMULAS. [bull.234 
Table 26. — For obtaining differences of altitude for any minute, etc. — Continued. 
40 
Corrections for 
C'urva- 
1 
2 
3 
4 
5 
6 
7 
8 
9 
ture, refraction 
. and i 
height of instrument.a 

369.2 
738 
1,108 
1,477 
1,846 
2,215 
2,584 
2,954 
3,323 
1 
370.8 
742 
1,112 
1,483 
1,854 
2,225 
2, 595 
2,966 
3,337 
Miles. 
Feet. 
Miles. 
Feet. 
2 
372. 3 
745 
1,117 
1,489 
1,862 
2,234 
2, 606 
2,978 
3,351 
1.6 
6 
10.2 
64 
3 
373.8 
748 
1,122 
1,495 
1,869 
2,243 
2,617 
2,991 
3, 365 
2.1 
7 
10.3 
65 
4 
375.4 
751 
1,126 
1, 502 
1,877 
2, 2,52 
2,628 
3,003 
3,378 
2.5 
8 
10.4 
67 
5 
376.9 
754 
1,131 
1,508 
1,885 
2,262 
2,639 
3,015 
3, 392 
2.8 
9 
10.5 
68 
6 
378.5 
757 
1,135 
1,514 
1,892 
2,271 
2,649 
3, 028 
3, 406 
3.1 
10 
10.6 
69 
7 
380.0 
760 
1,140 
1,520 
1,900 
2,280 
2,660 
3,040 
3,420 
3.4 
11 
10.7 
70 
8 
381.6 
763 
1,145 
1,526 
1,908 
2,289 
2,671 
3,053 
3,434 
3.6 
12 
10.8 
71 
9 
383.1 
766 
1,149 
.1,532 
1,916 
2,299 
2,682 
3,065 
3,448 
3.8 
13 
10.9 
73 
10 
384.7 
769 
1,154 
1,539 
1,923 
2,308 
2,693 
3,077 
3,462 
4.1 
14 
11.0 
74 
11 
386.2 
772 
1,159 
1,545 
1,931 
2,317 
2,703 
3,090 
3,476 
4.3 
15 
11.1 
75 
12 
387.7 
775 
1,163 
1,551 
1,939 
2,326 
2,714 
3,102 
3,490 
4.5 
16 
11.2 
77 
13 
389.3 
779 
1,168 
1,557 
1,946 
2,336 
2, 725 
3,114 
3,504 
4.7 
17 
11.3 
78 
14 
390.8 
782 
1,172 
1,563 
1,954 
2, 345 
2,736 
3,127 
3,517 
4.8 
18 
11.4 
79 
15 
392.4 
785 
1,177 
1,569 
1,962 
2, 354 
2,747 
3,139 
3,531 
5.0 
19 
11.5 
80 
16 
393.9 
788 
1,182 
1,576 
1,970 
2, 363 
2,757 
3,151 
3,545 
5.2 
20 
11.6 
82 
17 
395.5 
791 
1,186 
1,582 
1,977 
2,373 
2,768 
3,164 
3, 559 
5.4 
21 
11.7 
83 
18 
397.0 
794 
1,191 
1,588 
1,985 
2, 382 
2,779 
3,176 
3, 573 
5.5 
22 
11.8 
84 
19 
398.6 
797 
1,196 
1,594 
1,993 
2,391 
2,790 
3,188 
3,587 
5.7 
23 
11.9 
86 
20 
400.1 
800 
],200 
1,600 
2,000 
2,401 
2,801 
3,201 
3,601 
5.8 
24 
12.0 
87 
21 
401.6 
803 
1,205 
1,607 
2,008 
2, 410 
2,811 
3,213 
3,615 
6.0 
25 
12.1 
89 
22 
403.2 
806 
1,210 
1,613 
2,016 
2,419 
2,822 
3,225 
3,629 
6.1 
26 
12.2 
90 
23 
404.7 
809 
1,214 
1,619 
2,024 
2,428 
2,833 
3,238 
3,643 
6.3 
27 
12.3 
91 
24 
406.3 
813 
1,219 
1, 625 
2,031 
2,438 
2,844 
3, 2.50 
3, 656 
6.4 
'28 
12.4 
93 
25 
407.8 
816 
1,223 
1,631 
2,039 
2,447 
2, 855 
3,263 
3,670 
6.5 
29 
12.5 
94 
26 
409.4 
819 
1,228 
1,637 
2,047 
2,456 
2, 866 
3,275 
3,684 
6.7 
30 
12.6 
96 
27 
410.9 
822 
1,233 
1,644 
2,055 
2,465 
2,876 
3,287 
3,698 
6.8 
31 
12.7 
97 
28 
412.5 
825 
1,237 
1,650 
2,062 
2,475 
2,887 
3,300 
3,712 
6.9 
32 
12.8 
99 
29 
414.0 
828 
1,242 
1,656 
2,070 
2,484 
2,898 
3,312 
3,726 
7.0 
33 
12.9 
100 
30 
415.5 
831 
1, 247 
1,662 
2,078 
2,493 
2,909 
3,324 
3,740 
7.2 
34 
13.0 
102 
31 
417.1 
834 
1,251 
1,668 
2,085 
2, 503 
2,920 
3,337 
3,754 
7.3 
35 
13.1 
103 
32 
418.6 
837 
1,256 
1, 675 
2,093 
2, 512 
2,930 
3,349 
3,768 
7.4 
36 
13.2 
105 
33 
420.2 
840 
1,261 
1,681 
2,101 
2, 521 
2,941 
3,361 
3,782 
7.5 
37 
13.3 
106 
34 
421.7 
843 
1,265 
1,687 
2,109 
2, 530 
2, 952 
3,374 
3,796 
7.6 
38 
13.4 
108 
35 
423.3 
847 
1,270 
1,693 
2,116 
2, 540 
2,963 
3,386 
3,809 
7.8 
39 
13.5 
109 
36 
424.8 
850 
1,274 
1,699 
2,124 
2,549 
2,974 
3, 399 
3, 823 
7.9 
40 
13.6 
111 
37 
426.4 
853 
1,279 
1,705 
2,132 
2,558 
2,985 
3, 411 
3,837 
8.0 
41 
13.7 
112 
38 
427. 9 
856 
1,284 
1,712 
2,140 
2,567 
2, 995 
3. 423 
3,851 
8.1 
42 
13.8 
114 
39 
429.5 
859 
1,288 
1,718 
2,147 
2,577 
3,006 
3,436 
3,865 
8.2 
43 
13.9 
116 
40 
431.0 
862 
1,293 
1,724 
2,155 
2.586 
3,017 
3,448 
3,879 
8.3 
44 
14.0 
117 
41 
432.5 
865 
1,298 
1,730 
2, 163 
2,595 
3,028 
3, 460 
3,S93 
8.4 
45 
14.1 
119 
42 
434.1 
868 
1,302 
1,736 
2, 170 
2, 605 
3,039 
3,473 
3,907 
8.5 
46 
14.2 
120 
43 
435.6 
871 
1,307 
1,743 
2,178 
2, 614 
3,049 
3, 485 
3,921 
8.6 
47 
14.3 
122 
44 
437.2 
874 
1,312 
1,749 
2,186 
2,623 
3,060 
3, 498 
3,935 
8.7 
48 
14.4 
124 
45 
438.7 
877 
1,316 
1,7.55 
2,194 
2,632 
3,071 
3,510 
3,949 
8.8 
49 
14.5 
125 
46 
440.3 
881 
1,321 
1,761 
2,201 
2,642 
3,082 
3, 522 
3,963 
8.9 
50 
14.6 
127 
47 
441.8 
884 
1,325 
1,767 
2, 209 
2,651 
3,093 
3, 535 
3,976 
9.0 
51 
14.7 
129 
48 
443.4 
887 
1,330 
1,773 
2,217 
2,660 
3,104 
3,547 
3,990 
9.1 
52 
14.8 
130 
49 
444.9 
890 
1,335 
1,780 
2,225 
2,669 
3,113 
3,558 
4,003 
9.2 
53 
14.9 
132 
50 
446.5 
893 
1,339 
1, 786 
2,232 
2,679 
3,125 
3,572 
4,018 
9.3 
54 
15.0 
134 
51 
448.0 
896 
1,344 
1,792 
2, 240 
2,688 
3, 136 
3,584 
4,032 
9.4 
55 
15.1 
135 
52 
449.6 
899 
1,349 
1,798 
2,248 
2,697 
3,147 
3,596 
4,046 
9.5 
56 
15.2 
137 
63 
451.1 
902 
1,353 
1,804 
2,256 
2, 707 
3, 158 
3,609 
4,060 
9.6 
58 
15.3 
139 
54 
452.7 
905 
1,358 
1,811 
2, 263 
2,716 
3,169 
3,621 
4,074 
9.7 
59 
15.4 
141 
55 
454. 2 
908 
1,363 
1,817 
2,271 
2, 725 
3,179 
3,634 
4,088 
9.8 
60 
15.5 
142 
56 
455.8 
912 
1,367 
1,823 
2,279 
2,735 
3,190 
3,646 
4,102 
9.9 
61 
15.6 
144 
57 
457. 3 
915 
1,372 
1,829 
2,286 
2, 744 
3,201 
3,658 
4,116 
10.0 
62 
15.7 
146 
58 
458.8 
918 
1,377 
1,835 
2,294 
2,753 
3,212 
3,671 
4,130 
10.1 
63 
15.8 
148 
59 
460.4 
921 
1,381 
1,842 
2,302 
2,762 
3,223 
3,683 
4,144 
1.5.9 
16.0 
150 
151 
60 
461.9 
924 
1,386 
1,848 
2,310 
2,772 
3,234 
3,696 
4, 157 
a For all distances under 1.6 miles the correction may be taken as + 5 feet, 
is assumed 4.5 feet. 
Height of instrument 
