AZIMUTHS 



47 



the value of d as given, and the value of d used as a base, expressed to 

 the nearest tenth of a degree. This result is the declination correction. 



Repeat the above operations described for declination correction to 

 obtain latitude correction^ using an L difference of 1°. 



Find the algebraic sum of all the corrections and apply algebra- 

 ically to the base to obtain the interpolated value of Z. Convert this 

 Z to Zn according to rules previously given. 



68. Sample azimuth calculation. — Given the data below, find the 

 deviation of the compass using H. O. 71. 



L. A. T 0842.3. 



Declination, d 13°-23'.l N. 



Latitude, L 37°-16'.0 N. 



Z (p. s. c.) 108°.5. 



Variation from chart 6°. 5 W. 



Diff. for Corr. for + — 

 « S''- 17.7"= E. (L. A. T. 0842.3) 10'°= -118' 7.7"= 91' 



d 13°.4 N. 1°= -63' 0.4°= 25' 



L 37°.3 N. 1°= +51' 0.3° = 15' 



69. Use of United States Navy Hydrographic Office Publication 



H. O. 214. — In the H. O. 214 tables the meridian angle, t, is tabulated 

 under H. A. for every degree of arc (4 minutes of time), the latitude, 

 L, is given for each whole degree, and the declination, d, is given for 

 each one-half degree. These tables present altitudes (above 5°) and 

 azimuths for declinations up to 75°, and are therefore applicable for 

 use with the moon, planets, and navigational stars, as well as with the 

 sun. H. O. 214 is divided into 9 volumes, each volume covering 10° of 

 latitude. 



Interpolation for azimuth angles in H. O. 214 may be made in a 

 manner similar to that previously described for H. O. 71. 



