PREFACE 
These tables were conceived, and the method and formulas deduced, 
by Lieut. Commander J. Y. Dreisonstok, United States Navy, while 
a member of the Naval Examining Board, Navy Department, Wash- 
ington, D: C. This officer was later attached to the Division of 
Nautical Research of the Hydrographic Office, where he completed 
the calculations and put them into the present form. 
Commander F. H. Roberts, United States Navy, of the Hydro- 
graphic Office, contributed valuable suggestions and criticisms in the 
preparation and revision of the book. 
Acknowledgment is made for the constructive criticisms submitted 
by the fleet, the United States Naval Academy, and other sources. 
The work of revising the fifth edition-was performed by Mr. Elmer 
B. Collins of the Hydrographic Office. 
These tables are designed to facilitate the navigation of aircraft 
and surface craft. Used with the Nautical Almanac, no other books 
are required. 
The method of solving navigational problems here given is applied 
to all problems regardless of the position of the heavenly body, be it 
sun, moon, planet, or star. It requires few figures and gives a quick 
solution for determining (a) line of position, (6) compass error, (c) 
meridian altitude, (d) Great Circle course and distance, (¢) identifica- 
tion of unknown stars. The accuracy of the azimuth data fully 
justifies its use in obtaining compass error. The tables are simple to 
use. 
While a small and handy size is desirable, space is given at the end 
of the book to a full explanation of the construction of these tables, 
together with numerous problems, in order that an opportunity for 
analysis may be afforded those who desire to investigate their sound- 
ness and uses. 
W. R. GHERARDI, 
Rear Admiral, U. S. Navy, 
Hydrographer. 
Til 
Table 
