Astronomy: Determination of Time, Longitude, Latitude, and Azimuth (Classic Reprint)

From time to time during many years publications have been issued describing the
instruments and methods used by the Coast and Geodetic Survey in the determination of time,
longitude, latitude, and azimuth. The general aim has been to provide a working manual
which would serve as a guide to the observer in the field and the computer in the office in carrying
on the astronomic work of the Survey in a systematic manner. The exhaustion of previous
editions and the introduction of new instruments and methods have made necessary the suc-
cessive editions, in each of which much has been repeated from the preceding one.

Table of Contents

Introduction 5

PART I. -DETERMINATION OF TIME.

General remarks '. 7

Transit instrument 7

Transit micrometer f 8

Chronograph 11

Theory of the transit instrument 13

Adjustments of the transit instrument 14

Transit observations - 17

Computation of transit observations:

Usual method of computing time set 20

Second method of computing time set 28

Least square method of computing time set when azimuth stars are observed 39

Complete least square method of computing time set 41

Determination of instrumental constants 43

Discussion of errors 48

Other methods of determining time 51

The vertical circle 52

Star factors 60

PART II.- THE DETERMINATION OF THE DIFFERENCE OF LONGITUDE OF TWO STATIONS.

Introductory 78

Program and