CHAPTER IV

ASTRONOMICAL FOUNDATION OF TIME

Astronomical motions on which our time is founded. -- Reasons for selecting the sidereal day as a basis for our 24-hour day. -- Year of the seasons shorter than the zodiacal year. -- Precession of the equinoxes. -- Earth's rotation most uniform motion known to us. -- Time stars and transits. -- Local time. -- The date line. -- Standard time. -- Beginning and ending of a day. -- Proposed universal time. -- Clock dial for universal time and its application to business. -- Next great improvement in clocks and watches indicated. -- Automatic recording of the earth's rotation. -- Year of the seasons as a unit for astronomers. -- General conclusions Page 53

ILLUSTRATIONS

Page Portrait of James Arthur 8

Interpretation of Chinese and Japanese Methods of Time Keeping 15

Portable Bronze Sundial from the Ruins of Herculaneum 16

Noon-Mark Sundials 17

Modern Horizontal Sundial for Latitude 40°-43´ 18

The Earth, Showing Relation of Dial Styles to Axis 18

Modern Sundial Set Up in Garden 18

"Time-Boy" of India 19

"Hon-woo-et-low," or "Copper Jars Dropping Water"--Canton, China 19

Modern Sand Glass or "Hour Glass" 20

Tower of the Winds, Athens, Greece 20

Key to Japanese Figures 25

Japanese Dials Set for Long and Short Days 25

Japanese Striking Clock with Weight and Short Pendulum 26

Japanese Striking Clock with Spring, Fusee and Balance 26

Japanese Clock with Vertical Dial, Weight and Balance 27

Japanese Clock with Vertical Dial Having Curved Lines, Weight and Balance 27

Japanese Vertical Dials 28

Japanese Striking Clock with Two Balances and Two Escapements 29

"Twelve Horary Branches" and "10 Celestial Stems" as Used in Clocks 30

Key to "12 Horary Branches" and "10 Celestial Stems" 30

Dial of Japanese Astronomical Clock 31

Use of "Yeng Number" and Animal Names of Hours 32

Public Dial by James Arthur 37

Dial of Philadelphia City Hall Clock 37

Verge Escapement 37

De Vick's Clock of 1364 38

Anchor Escapement 38

American Anchor Escapement 39

Dead Beat Escapement 39

Remontoir Clock by James Arthur 40

Remontoir Clock Movement 40

Antique Clock, Entirely Hand-Made 41, 42

Double-Case Watch of Repoussé Work 42

Triple-Case Turkish Watches 43

Watch Showing Dutch Art Work 43

Triple-Case Turkish Watch 44

Watches Showing Art Work 45

Antique Watch Cock 46

"Chinese" Watch 46

Musical Watch, Repeating Hours and Quarters 47

Syrian Dial 47

Hebrew Numerals 48

Twenty-four Hour Watch 48

Domestic Dial by James Arthur 49

Local Time--Standard Time--Beginning and Ending of the Day 57

Universal Time Dial Set for Four Places 61