270 GEOGRAPHIC TABLES Al^D FORMULAS. [bull. 234. 
Table 26. — For obtaining differences of altitude for any minute, etc. — Continued. 
0^. 
Corrections for curva- 
1 
2 
3 
4 
6 
(> 
7 
s 
9 
ture, refraction, and 
height of instrument." 
1 
1.5 
3.1 
5 
6 
8 
9 
11 
12 
14 
Miles. 
Fed. 
Miles. 
Feet. 
3.1 
6.1 
9 
12 
15 
18 
22 
25 
28 
1.6 
6 
10.2 
64 
3 
4. iS 
9.2 
14 
18 
23 
28 
32 
87 
41 
2.1 
7 
10.8 
65 
4 
6.1 
12.3 
18 
25 
31 
37 
43 
49 
55 
2.5 
8 
10.4 
67 
5 
7. 7 
15.4 
23 
81 
38 
46 
54 
61 
69 
2.8 
9 
10.5 
68 
6 
9.2 
18.4 
28 
87 
46 
55 
65 
74 
83 
3.1 
10 
10.6 
69 
7 
10.8 
21.5 
32 
48 
54 
65 
75 
86 
97 
3.4 
11 
10.7 
70 
8 
12.3 
24.6 
87 
49 
61 
74 
86 
98 
111 
8.6 
12 
10.8 
71 
9 
13.8 
27.6 
41 
55 
69 
88 
97 
111 
124 
8.8 
18 
10.9 
73 
10 
15.4 
30.7 
46 
■ 61 
77 
92 
108 
128 
138 
4.1 
14 
11.0 
74 
11 
16.9 
33.8 
51 
68 
84 
101 
118 
185 
152 
4.8 
15 
11. 1 
75 
12 
18.4 
86.9 
55 
74 
92 
111 
129 
147 
166 
4.5 
16 
11.2 
77 
13 
20.0 
39.9 
60 
80 
■ 100 
120 
140 
160 
180 
4.7 
17 
11.3 
78 
14 
21.5 
43.0 
65 
86 
108 
129 
151 
172 
194 
4.8 
18 
11.4 
79 
15 
23.0 
46.1 
69 
92 
115 
138 
161 
184 
207 
5.0 
19 
11.5 
80 
16 
24.6 
49.1 
74 
98 
123 
147 
172 
197 
221 
5.2 
20 
11.6 
82 
17 
26.1 
52. 2 
78 
104 
181 
157 
183 
209 
285 
5.4 
21 
11.7 
83 
18 
27.6 
55.3 
83 
111 
138 
166 
194 
221 
249 
5.5 
22 
11.8 
84 
19 
29.2 
58.4 
88 
117 
146 
175 
204 
233 
263 
5.7 
23 
11.9 
86 
20 
30.7 
61.4 
92 
128 
154 
184 
215 
246 
276 
5.8 
24 
12.0 
87 
21 
32.3 
64.5 
97 
129 
161 
194 
226 
258 
290 
6.0 
25 
12.1 
89 
22 
33.8 
67.6 
101 
135 
169 
208 
237 
270 
304 
6.1 
26 
12.2 
90 
23 
35. 3 
70.7 
106 
141 
177 
212 
247 
283 
318 
6.3 
27 
12.3 
91 
24 
36.9 
78.7 
111 
147 
184 
221 
258 
295 
332 
6.4 
28 
12.4 
93 
25 
38.4 
76.8 
115 
154 
192 
280 
269 
307 
346 
6.5 
29 
12.5 
94 
26 
39.9 
79.9 
120 
160 
200 
240 
280 
319 
359 
6.7 
80 
12.6 
96 
27 
41.5 
82.9 
124 
166 
207 
249 
290 
332 
373 
6.8 
31 
12.7 
97 
28 
43.0 
86.0 
129 
172 
215 
258 
301 
344 
387 
6.9 
32 
12.8 
99 
29 
44.5 
89.1 
134 
178 
223 
267 
312 
356 
401 
7.0 
38 
12.9 
100 
30 
46.1 
92.2 
188 
184 
230 
276 
823 
369 
415 
7.2 
84 
13.0 
102 
31 
47.6 
95.2 
143 
190 
238 
286 
388 
881 
429 
7.3 
35 
18.1 
108 
82 
49.2 
98.3 
147 
197 
246 
295 
344 
393 
442 
7.4 
36 
13.2 
105 
33 
50.7 
101.4 
152 
208 
258 
804 
355 
405 
456 
7.5 
37 
18.3 
106 
34 
52.2 
104.4 
157 
209 
261 
818 
366 
418 
470 
7.6 
38 
13.4 
108 
35 
53.8 
107.5 
161 
215 
269 
828 
876 
430 
484 
7.8 
39 
13.5 
109 
36 
55.3 
110. 6 
166 
221 
276 
332 
387 
442 
498 
7.9 
40 
13.6 
111 
37 
56.8 
118.7 
170 
227 
284 
341 
398 
456 
512 
8.0 
41 
13.7 
112 
38 
58.4 
116.7 
175 
233 
292 
350 
409 
467 
525 
8.1 
42 
13.8 
114 
39 
59.9 
119.8 
180 
240 
800 
359 
419 
479 
539 
8.2 
43 
13.9 
115 
40 
61.4 
122.9 
184 
246 
307 
369 
430 
492 
553 
8.3 
44 
14.0 
117 
41 
63.0 
125. 9 
189 
252 
315 
378 
441 
504 
567 
8.4 
45 
14.1 
119 
42 
64.5 
129. 
194 
258 
823 
387 
452 
516 
581 
8.5 
46 
14.2 
120 
43 
66.0 
132.1 
198 
264 
380 
396 
462 
528 
594 
8.6. 
47 
14.3 
122 
44 
67.6 
185. 2 
208 
270 
338 
405 
473 
541 
608 
8.7 
48 
14.4 
124 
45 
69.1 
138. 2 
207 
276 
346 
415 
•484 
553 
622 
8.8 
49 
14.5 
125 
46 
70.6 
141.3 
212 
283 
358 
424 
495 
565 
636 
8.9 
50 
14.6 
127 
47 
72. 2 
144.4 
217 
289 
361 
433 
505 
578 
650 
9.0 
51 
14.7 
129 
48 
73.7 
147. 5 
221. 
295 
369 
442 
516 
590 
664 
9.1 
52 
14.8 
180 
49 
75.3 
150. 5 
226 
301 
376 
452 
527 
602 
677 
9.2 
53 
14.9 
182 
50 
76.8 
153.6 
280 
307 
384 
461 
538 
614 
691 
9.3 
54 
15.0 
134 
51 
78.3 
156.7 
235 
313 
892 
470 
548 
627 
705 
9.4 
55 
15.1 
135 
52 
79.9 
159.7 
240 
319 
399 
479 
559 
639 
719 
9.5 
56 
15.2 
137 
53 
81.4 
162. 8 
244 
826 
407 
488 
570 
651 
738 
9.6 
58 
15.3 
139 
54 
82.9 
165. 9 
249 
382- 
415 
498 
581 
664 
747 
9.7 
59 
15.4 
141 
55 
84.5 
169.0 
253 
338 
422 
507 
591 
676 
760 
9.8 
60 
15.5 
142 
56 
86.0 
172.0 
258 
844 
480 
516 
602 
688 
774 
9.9 
61 
15.6 
144 
57 
87.5 
175. 1 
263 
350 
438 
525 
613 
700 
788 
10.0 
62 
15.7 
146 
58 
89.1 
178.2 
267 
356 
445 
535 
624 
718 
802 
10.1 
63 
15.8 
148 
59 
90.6 
181.8 
272 
368 
458 
544 
634 
725 
816 
15.9 
16.0 
150 
151 
60 
92.2 
184.8 
276 
369 
461 
553 
645 
737 
829 
"For all distances under 1.6 miles the correction maybe taken as +5 feet, 
is assumed 4.5 feet. 
Height of instrument 
