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UC-NRLF 



D 




fl7E 



EX-MERIDIAN CALCULATOR. 



JAMES SMITH. Master Mariner, 



Complete Tables for finding the Latitude by an Ex- 
Meridian Altitude of the Sun, Planet or Star, within the 
Latitudes and Declinations of 81 North and South, and 
within all practical limits of Hour Angle. 

By using these Tables, the correct Latitude can be 
obtained by observing Stars at twilight when they are 
near the Meridian, and* when the horizon is then quite 
ctear, 



vB 

^-, c 

^ 



a.nd extended Edition. 

PRICE-FOUR SHILLINGS. 






PUBLISHED AND SOLD BY 



HENRY HUGHES & SON, Ltd., 

marine Opticians, 

The Port of London Navigation Stores, 

59, FENCHURCH STREET, 



ALSO BY THE SAME AUTHOR 

THE OFF-SHORE DISTANCE CALCULATOR, 2/6, 



Table 1. 




HOUR ANGLE NUMBERS. Q3 


\ 

~r 


Table 2. oont. 


HOUR 


1 HOUR 


cTV C^"*^ 
ottkP^LAT. AND DEC. Numbers. 
\jS5r 


Min. 0* 1 


a* : 




30"* 


40^ 


50^ 1 


Min. 


0" 1 


LO" , 


20" 2 


,0" 4 


0" E 


" 


eg- 


0' 


10' 


20' 


30' 


40' 


50' 





4856 


4503 


4254 


^oeo o ; 


548 ; 


546 


543 


540 C 


538 ; 


536 


21 


30 


30 


31 


31 


32 


32 


1 3901 


3767 36,52 


3549 3458 


5375 1 333 331 


329 


526 324 322 


22 


33 


33 


34 


34 


35 


35 


2 3299 


3230 3165 : 3106 3049 


2997 2 319 317 


315 312 310 308 


23 


36 


3V 


37 


38 


38 


39 


3 2947 


2900 2856 2813 ' 


2773 


2734 3 305 303 


301 299 296 294 


24 


39 


40 


40 


41 


42 


42 


4 2697 


2662 2628 


2595 


2563 


2533 4 292 


290 287 


285 283 281 


85 


43 


43 


44 


4b 


45 


46 


5 2503 


2475 2447 


2421 


2395 


2370 5 278 276 274 272 270 267 


26 


46 


47 


48 


48 


49 


49 


6 2345 


2321 i 2298 


2276 


2254 


2232 6 265 263 j 261 259 257 254 


27 


50 


51 


51 


52 


53 


53 


7 2211 


2191 ! 2171 


2151 


2132 


2114 7 252 250 248 246 244 242 


28 


b4 


55 


55 


56 


57 


57 


8 2095 2077 j 2060 
9 1993 1977 1961 


2043 
1946 


2026 
1931 


2009 8 240 237 235 233 231 229 
1916 9 227 225 223 221 219 217 


29 
30 


b8 
62 


59 
63 


60 
64 


60 

65 


61 
65 


62 
66 


10 1901 
11 1819 
12 1743 
13 1674 
14 1609 


1887 
1806 
1731 
1663 
1599 


1873 
1793 
1719 
1652 
1589 


1859 
1780 
1708 
1641 
1579 


1845 
1767 
1696 
1630 
1569 


1832 10 215 213 210 208 206 204 
1755 11 202 200 198 196 194 192 
1685 12 190 188 186 184 182 180 
1620 13 178 176 174 173 171 169 
1559 14 167 i 165 j 163 161 j 159 j 157 | 


31 
32 
33 
34 
35 


67 
72 
76 
81 
87 


68 
72 
77 
82 
88 


68 
73 
78 
83 
88 


69 
74 
79 
84 
89 


70 
75 
80 
85 
90 


71 
76 
81 
86 
91 


15 1549 
16 1493 
17 1441 
18 1391 
19 1344 


1540 
1484 
1432 
1383 
1337 


1530 
1475 
1424 
1375 
1329 


1521 
1467 
1416 
1367 
1322 


1512 
1458 
1407 
1359 
1314 


1502 15 
1449 16 
1399 17 
1352 18 
1307 19 i 


155 153 151 149 148 
144 i!42 140 1138 i 136 , 
132 131 129 -127 125 
121 120 118 116 114 
110 : 109 i 107 | 105 103 


146 
134 
123 
112 
101 


36 
37 
38 
39 
40 


92 
98 
103 
109 
116 


93- 
99 
104 
111 

117 


94 
100 
105 
112 
118 


95 
101 
106 
113 
119 


96 
102 
107 
114 
120 


97 
102 
108 
115 
121 


20 1300 

21 1257 
22 1217 
23 1178 
24 1141 


1292 
1250 
1210 
1172 
1135 


1285 

1244 
1204 
1166 

1129 


1278 
1237 
1197 
1160 
1123 


1271 
1230 
1191 
1154 
1118 


1264 
1223 
1185 
1147 
1112 


20 
21 
22 
23T 
24 


100 
89 
78 
68 
58 


98 
87 
77 
66 
56 


96 
85 
75 
65 
54 


94 
84 
73 
63 
53 


92 
82 
71 
61 
51 


91 
80 
70 
59 
49 


41 

42 
43 
44 
45 


122 
129 
136 
143 
151 


123 
130 
137 
144 
152 


124 
131 
138 
146 
153 


126 
132 
139 
147 
154 


127 
134 
141 
148 
156 


128 
135 
142 
149 
157 


25 1106 
26 1072 
27 1039 
28 1008 
29 977 


1100 
1066 
1034 
1002 
972 


1094 
1061 
1029 
997 
967 


1089 
1055 
1023 
992 
962 


1083 
1050 
1018 
987 
957 


1077 
1045 
1013 
982 
953 


25 
26 
27 
28 
29 


48 
37 
28 
18 
8 


46 44 
36 34 
26 ' 24 
16 15 
6 5 


43 
33 
23 
13 
3 


41 
31 

21 


39 
29 
19 
10 

o 


46 
47 
48 
49 
50 


158 
166 
174 
183 
192 


160 
168 
176 
185 
193 


161 
169 
177 
186 
195 


162 
170 
179 
187 
196 


164 
172 
180 
189 
198 


165 
173 
182 
190 
200 


30 948 
31 919 
32 892 
33 865 
84 839 


943 
915 
887 
861 
835 


938 
910 
883 
856 
831 


933 
905 
878 
852 
826 


929 
901 
874 
848 
822 


924 
896 
870 
843 
818 


Note. The Hour Angle in Minutes 
must not exceed the Meridian Zenith 
Distance in Degrees. 


51 
52 
53 
54 
55 


201 
211 
221 
231 
241 


203 
J212 
222 
233 
243 


204 
214 
224 
234 
245 


206 

216 
226 
236 
247 


207 
217 
;227 
,238 
!249 


209 
219 
229 
240 
251 


TABLE 2. 


35 814 
36 790 
37 766 
38 743 
39 720 


810 

786 
762 
739 
717 


806 
782 
758 
735 
713 


802 
778 
754 
731 
709 


798 
774 
750 
728 
706 


794 
770 
747 
724 
702 




LAT. and DEC. Numbers 




56 
57 
58 
59 
80 


252 
264 
276 
288 
301 


254 
266 

278 
290 
303 


256 
268 
280 
292 
305 


258 
270 
282 
295 
308 


272 
284 
!297 
310 


262 
274 
'286 
299 
312 


Deg. 


0' 


10' 


20' 


30' 


40' 


50' 
















40 698 
41 677 
42 656 
43 636 
44 616 


695 
673 
653 
632 
613 


691 

! 670 

: 649 

629 
609 


688 
666 
646 
626 
606 


684 
663 
642 
622 
603 


681 
660 
639 
619 
600 


1 

2 
3 
4 
5 























1 


61 
62 
63 
64 
65 


314 
328 
343 
358 
374 


317 
331 
345 
361 

377 


319 

333 

348 
363 
380 


321 
336 
350 
366 
382 


324 
338 
353 
369 

385 


326 
340 
356 
371 
388 


1 

2 


1 

2 


1 

2 


1 

2 


1 

2 


2 
2 


45 596 
46 577 
47 559 
48 541 
49 523 


593 

574 
556 
538 
520 


590 
571 
553 
535 
517 


587 
568 
550 
532 
514 


584 
565 
547 
529 
511 


580 6 
562 7 
544 8 
526 9 
508 10 


2- 
3 
4 
5 
7 


3 
3 
4 
6 
7 


3 
4 
5 
6 
7 


3 
4 
5 
6 
7 


3 
4 
5 
6 
8 


3 
4 
5 
6 
8 


66 391 
67 408 
68 426 
69 446 
70 466 


394 
411 
430 
449 
469 


396 
414 
433 
452 
473 


399 
417 
436 
456 
477 


402 
420 
439 
459 
480 


405 
423 
442 
462 
484 


50 505 
51 488 
52 471 
53 455 
54 439 


502 
485 
468 
452 
436 


499 
482 
466 
449 
433 


497 
480 
463 
447 
431 


494 
477 
460 
444 
428 


491 11 
474 12 
457 13 
441 14 
425 15 


8 
10 
11 
13 
15 


8 
10 
12 
13 
15 


9 
10 
12 
14 
16 


9 
10 
12 
14 
16 


9 
11 

12 

14 
16 


9 
11 
13 
15 
17 


71 487 491 495 
72 510 i 514 518 
73 534 538 542 
74 560 564 569 
75 587 ;592 j 597 


499 
522 
547 
573 
601 


502 
526 
551 
578 
606 


506 
530 
555 
582 
611 


55 423 
56 407 
57 392 
58 377 
59 362 


42T 118 
40o . ' 402 
389> 387 
3&B 372 
36(7 357 


415 1 412 
399 397 
384 ! 382 
369 367 
355 352 


410 16 
394 17 
379 18 
365 19 
350 20 


17 
19 
22 

24 
27 


18 
20 
22 
25 
1 27 


18 

20 
23 
25 
28 


18 
21 

23 
26 
28 


19 
21 

23 
i 26 
29 


19 

21 
24 
27 
29 


76 616 621 627 
77 648 653 659 
78 682 688 1694 
79 719 726 733 
80 760 768 ! 775 


632 537 
665 670 
700 707 
739 (746 
782 1790 


i642 
676 
713 
753 
798 















vn o-7r^t- 




Table 3. 


ALTITUDE NUMBERS 




Table 4. 







ALTITUDE. 






ALTITUDE. 




ANGLE. 




Deg. 


0' 10' 


20' 


30' 


40' 


50' 


Deg 


. 0' 


10' 


20' 


30^ 


40' 


50' 


Mins. 


87 


88 9 ! 


89 




















1 














1 




5 


1282 


1281 


1281 


1281 


1281 


1281 


66 


888 


885 


882 


879 


876 


874 





1445 


1621 


1922 


g 


1281 1281 


1280 


1280 


1280 


1280 67 


871 868 


865 861 i 858 < 855 


1 


1447 


1624 


1930 


7 


1280 


1279 


1279 1279 


1279 1279 68 


852 849 846 ', 843 839 836 


2 


1450 1628 


1937 


g 


1279 


1278 


1278 


1278 


1278 1278 69 


833 830 826 


823 


819 816 


3 


1452 


1632 


1944 


9 


1277 


1277 


1277 


1277 


1277 


1276 ; 70 


812! 809 805 


802 


798 


795 


4 


1454 


1636 


1952 


10 


1276 


1276 1276 


1275 


1275 


1275 1 71 


791 787 784 780 776 j 772 


5 


1457 


1639 


1968 


11 


1274 


1274 


1274 1274 


1273 


1273 72 


7681 764 760 756 752 748 


6 


1459 


1643 


1968" 


12 


1273 1273 


1272 


1272 


1272 1271 73 


744 740 


736 732 727 723 


7 


1462 


1647 


1976 


13 


1271 1271 


1270 


1270 


1270 1269 74 


719 ' 714 


710 


705 700 696 


8 


1464 


1651 


1984 


14 


1269 


1269 


1268 


1268 


1268 


1267 75 


691 


686 


682 


677 


672 


657 


9 


1467 


1655 


1992 


15 


1267 


1267 1266 1266 


1266 


1265 76 


662 


657 


651 


646 


641 


636 


10 


1470 


1659 


2001 


16 


1265 1265 1264 1264 


1263 1263 77 


630 625 619 613 


608 602 


11 


1472 


1663 


2010 


17 


1263 1262 1262 j 1261 


1261 


1261 | 78 


596 590 584 578 


572 566 


12 


1475 


1667 


2019 


18 


1260 1260 1259 


1259 


1258 


1258 


79 


559 553 546 539 


532 


525 


13 


1477 


1671 


2028 


19 


1257 1257 1257 


1256 


1256 


1255 


80 


518 


511 


503 


496 


488 


480 


14 


1480 


1675 


2037 


20 


1255 1254 


1254 1253 


1253 


1252 


81 


473 


464 456 


448 


439 431 15 


1483 


1679 


2047 


21 


1252 1251 ! 1251 1250 


1250 


1249 82 


422 413 404 


394 


384 374 16 


1485 


1683 


2057 


22 


1249 


1248 1248 1247 


1246 


1246 83 


364! 354 343 


332 321 309 17 


1488 


1687 


2067 


23 


1245 


1245 ; 1244 1244 


1243 


1243 I 84 


297 285 272! 259 > 246 232 | 18 


1490 


1691 


2077 


24 


1242 


1241 1241 . 1240 


1240 


1239 ' 85 


; 218 203 188 172 i 156 139 


19 


1493 


1696 


2087 


25 


1238 


1238 


1237 


1237 


1236 


1235 86 


12l] 103 


83 


63 


42 


20 


20 


1496 


1700 


2098 


(M 




1 9^4 


1233 


1233 


1232 














21 


1499 


1704 


2109 


BO 

27 


1231 


1230 


1230 


1229 


1228 1 1228 


Sun's Altitude Correction (Add). 


22 


1501 


1709 


2120 


no 


1 f-jrjrr 


I 00 


loot; 


TOOK 


1224 1223 






23 


: 1504 


1713 


2132 


ao 

29 


1223 


JLoaO 

1222 


.LOAMJ 

1221 


oav 

1221 


1220 1219 




Height of Eye in Feet. 


24 


1507 


1718 


2144 


30 


1218 


1218 


1217 1216 


1215 1215 


< 


15 


20 


30 


40 


50 


65 


25 


1510 


1722 


2156 


31 


1214 


1213 ! 1212 1211 


1211 i 1210 
















26 


i 1512 ! 1727 


2169 


32 


1209 1208 1207 1207 


1206 1205 


6 


3.9 


3.31 


2.3 


1.5 


0.7 




27 


, 1515 


1732 


2181 


33 


1204 1203 1203 , 1202 


1201 1200 j 7 


5.0 


4.4 


3.4 


2.6 


1.9 


0.9 


28 


1518 


1736 


2195 


34 


1199 


1198 1 1197 j 1196 


1195 1195 8 


5.8 


5.3 


4.3 


3.5 


2.7 


1.7 


29 


j 1521 


1741 


2209 


35 


1194 


1193 


1192 1191 


1190 i 1189 9 


6.5 


6.0 


5.0 


4.1 


3.4 


2.4 


30 


1524 


1746 


2223 


36 


1188 


1187 1186 I 1186 


1185 1 1184 


10 


7.1 


6.5 


5.5 


4.7 


4.0 


3.0 


31 


1527 


1751 


2238 


37 


1183 1182 ; 1181 1180 


1179 


1178 


12 


8.0 


7.4 


6.4 


5.5 


4.8 


3.9 


32 


1530 


1756 


2253 


38 


1177 1176 1175 1174 


! 1173 1172 


14 


8.6 


8.0 


7.0 


6.2 


5.5 


4.5 


33 


1533 


1760 


2269 


39 


1171 1170 


1169 1168 


1166 1165 


16 


9.1 


8.5 


7.5 


6.7 


5.9 


5.0 


34 


1536 


1765 


2285. 


40 


1164 1163 j 1162 1 1161 


> 1160 


1159 


20 


9.7 


9.2 


8.2 


7.3 


6.6 


5.6 


35 


1539 


1771 


2302 


41 


1158 1157 1156 1154 


1153 


1152 24 


10.2 


9.6 


8.6 


7.8 


7.1 


6.1 


36 


! 1542 1776 


2320 


42 


1151 1150 1149 : 1148 


1146 1145 || 30 


10.7 10.1 


9.1 


8.3 


7.6 


6.6 37 


1545 1781 


2338 


43 


i 1144 


1143 1142 1140 


1139 1138 40 


11.2 10.6 


9.6 


8.8 


8.0 


7.1 38 


1548 1786 


2358 


44 


1137 


1135 1134 1133 


: 1132 


1130 


60 


11.7 


11.1 


10.1 


9.3 


8.6 


7.7 39 


1551 


1792 


2378 


45 


| 1129 1128 1 1127 1125 


1124 


1123 


90 


12.2 


11.6 


10.6 


9.8 


9.1 


8.1 


40 


: 1554 1797 


2399 


Aft 


1191 1190 1119 


1118 


1116 


1115 


















1557 1802 


2421 


TfO 

47 


j XJLIJL LLci\j m,y 

1113 1112 1111 


1109 


1108 


1106 


Star's Altitude Correction (Subt.) 


42 


1560 1808 


2445 


48 


1105 1104 1102 1101 


| 1099 1098 






43 


1563 1814 


2470 


T!O 

49 


1096 1095 1093 1092 


j 1090 


1089 




Height of Eye in Feet. 


44 


1566 1819 


2496 


50 


1087 1086 i 1084 j 1083 


1081 | 1080 


5 


15 


20 


30 


40 


50 


65 


45 


1570 1825 


2524 


51 


1078 1077 1075 


1073 


1072 1070 
















46 


1 1573 1831 


2554 


52 


1069 1057 1065 1064 


10S2 1060 


6 


12.3 


12.9 


13.9 


14.7 


15.4 


16.4 


47 


! 1576 1837 


2586 


53 


1059 1057 1055 1053 


I 1052 


1050 7 


11.2 


11.8 


12.8 


13.6 


14.3 


15.3 


48 


1579 1843 


2621 


54 


j 1048 1046 1045 1043 


| 1041 


1040 8 


10.4 11.0 


12.0 


12.8 


13.5 14.5 49 


I 1583 1849 


2659 


55 


j 1038 1036 1034 1032 


1030 


1029 j 9 


9.7 10.3 


11.3 


12.1 


12.8 13.8 I 50 


1586 1855 


2700 


56 


1027 1025 ! 1023 i 1021 


1019 


1017 


10 


9.1 9.7 10.7 


11.5 


12.3 13.2 51 


1589 1861 


2746 


57 


! 1015 1013 1011 1009- 


1QQ7 " 


1005 


12 


8.3 8.9 9.8 


10.7 11.4112.4 52 


: 1593 1867 


2797 


58 


i 1003 


1001 1 999 1 997 


995 993 | 14 


i 7.6 1 8.2 9.2 


10.0 110.8 ill. 7 53 


1596 1874 


2855 


59 


| 991 


989 


987 


984 


982 


980 


16 


7.1 


7.7 8.7 


9.5 10.3 11.2 54 


1600 


1880 


2922 


60 


j 978 


976 


974 


971 


969 


967 


20 


6.4 


7.0 


8.1 


8.8 


9.6 


10.5 55 


1603 


1887 


3001 


61 


i 964 


962 


960 


958 


955 


953 24 


6.0 


6.5 


7.5 


8.4 9.1 10.1 56 


1607 1894 


3098 


62 


: 950 


948 946 943 


: 941 938 30 


5.5 j 6.1 7.0 


7.9 8.6 9.6 5^ 


: 1610 1901 


3223 


63 


, 936 ; 933 931 928 


926 923 40 


5.0 ! 5.5 6.5 


7.3 8.1 9.0 t>; 


;1614 1908 


3399 


64 


1 921 i 918 i 915 1 913 


910 j 907 j 60 


' 4.4 ! 5.0 5.9 


6.8 7.5 8.5 5# 


' 1617 1915 


3700 


65 


i 905 ; 902 899 


896 


894 891 90 


3.8 4.4 


5.4 


6.2 6.9 


7.9 6Q- 


J621 1922 


Infinite. ' 




. 
' 














3 


r 





i-IBRARY 

RULES ANE> EXAMPLES. 



To work an ex-meridian of the Sun, Planet or Star : 

Correct the observed Altitude by adding the Sun's correction, or subtract- 
ing the Star's correction. 

Take from the Tables numbers corresponding to the Hour Angle, Latitude 
by account, Declination and True Altitude. Add these four numbers together. 
From Table 4 takeout the Angle corresponding to the sum of the numbers. 
From this Angle subtract the True Altitude. The remainder will be the 
Meridian Zenith Distance. Apply the Declination in the usual way, and the 
Latitude found will be the Latitude at the time of the observation. 

EXAMPLE. Hour Angle oh 30111, Latitude by account 40 10' N., Declina- 
tion 10 o' 8., True Altitude 39 20' S. 



Hour Angle number 
Lat. by ace. do. 
Declination do. 
True Altitude do. 



948. 
ii7 
7 
1169 

2241 
2241, Table 4 = Angle 89 ' : 



Angle, Table 4 ... 
True Altitude 



89 31' 
39 20 S. 



Meridian Zenith Dist. 50 nN. 
Declination ... 10 oo S. 



Latitude 



40 



n'N. 



If an Altitude near the meridian be observed below the pole, find the Angle 
in Table 4 as above. From this Angle subtract the Declination, and to the 
remainder add the Altitude. This sum will be the Latitude at the time of the 
observation. 

EXAMPLE. Hour Angle 43m 483, Latitude by ace. 54 10' S., Declination 
60 23' S. True Altitude of a Centauri below the pole 24 55'. 



Hour Angle number 
Latitude by ace. do. 
Decliualion do. 

True Altitude do. 



619 

233 
' 306 
1239 

2397 



Angle, Table 4 
Declination 



True Altitude 
Latitude 



89 40' 

60 23 S. 

29 17 

24 55 



54 



' S. 



2397, Table 4 = Angle 89 40'