. Tables of calculated hour-angles and altitude azimuth table 30N. to 30S. : ex-meridian tables 60N. to 60S. and calculated reductions ans azimuths of bright stars from 1 hour to 3 hours from Meridian / c by Blackburne . Mer. Alt. 41 220 N.+ 1 467 43 87 46 513 2. 16 20 3 N. Approx. Lat. 30 31*0 for 31 +i3 (interpolation) Lat. in 30 32-3 S. Azimuth from Table (p. 292) N. 17^° E. gives (Table IV., p. 260)Lat. Var. i45s., which gives (Tabfe VL) for PlaneChart S. 74°^ E. To make certain that the right stars are observed, the approxi-mate altitudes a
. Tables of calculated hour-angles and altitude azimuth table 30N. to 30S. : ex-meridian tables 60N. to 60S. and calculated reductions ans azimuths of bright stars from 1 hour to 3 hours from Meridian / c by Blackburne . Mer. Alt. 41 220 N.+ 1 467 43 87 46 513 2. 16 20 3 N. Approx. Lat. 30 31*0 for 31 +i3 (interpolation) Lat. in 30 32-3 S. Azimuth from Table (p. 292) N. 17^° E. gives (Table IV., p. 260)Lat. Var. i45s., which gives (Tabfe VL) for PlaneChart S. 74°^ E. To make certain that the right stars are observed, the approxi-mate altitudes and bearing of both stars may be quickly calculated,or taken from the table almost at sight. The final calculation of ships position may be calculated readilyviithout the aid of the Chart, as follows :— Lat. (i) 30 OD*o (2) 30 32-3 S. Az. N. 837 E. gives 782 to Io of N. 17*5 E. gives ©?28 to io of Long. D. Lat. 32*3 Lat. Error754 D. Lat. Error 7 54 Long.: io Long. Cor,43 E. 43Xo28 gives Lat. Cor. i2 S. Lat. (2) 30 32-3 I 2 S. Long, at 2nd Obs. 106 4*5 4-3 E. Lat. in 30 33-5 S. f~ Long, in io6 8-8 E. Cor. + 6*67 L. Var-51 gives for PlaneChart (Table VI.) S. 7^° 106 8-7 E. EXAMPLES IN THE USE OF THE TABLES XXXIX POSITION FROM COMBINED EX-MERIDIAN OBSERVATIONS OF TWO STAR REDUCTION TABLES 1913.—March iiih, shortly after sunset, at about 6h. , at ship, at lat. 47° N. andlonjr. 6° W. Suppose a chronometer to indicate Green. 6 h. 35 m. 47 s., when the true altitude of-Vc Aldebaran was 57 6 to south-westward of mer. ; and again, after running N. 28° E. (true) for i milethe chronometer indicated Green. 6 h. 40 m. 55 s., when the true altitude of -;;- Sirius was 24 14 south-eastward of mer. Required the position of ship at time of 2nd Observation. Al-DEBARAN TO SoUTH-WESTWARD. H. M. S. Green. 6 35 47Long. 6° W. - 24 o H. M. T, (Green, noon) 23 14 9*53Accl. 6 h. 35j m.
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