Part 19

Longitude, counted East and West, 125 determining, 6 determining by occultations, 167 effect on time differences, 123 explained, 123 of Washington, first determined, 168

Maclear, observes Eta Argus, 205

Magnitudes, stellar, 91

Manila, its time, 127

Maps, astronomical side of, 112

Meridian circle, explained, 189

Milky-way, poor in nebulæ, 33

Minor Planets, see Asteroids.

MOON, HOAX, 199 motion among stars, 163 mountains discovered by Galileo, 49 size of, measured, 166

Motion of moon, 163

MOTIONS of the EARTH'S Pole, 131

MOUNTING GREAT TELESCOPES, 170

Naked-eye nebulæ, 28

Naples, Royal Observatory, latitude observations, 139

Naval Observatory, Washington, noon signal, 120

NAVIGATION, 1 before chronometers, 3 use of astronomy in, 113

NEBULÆ, 27

Nebula, in Andromeda, 28 in Orion, 30 "keyhole", 205

Nebular, hypothesis, 33 structure in Pleiades, 17

Nebulous stars, 31

Negative, and positive, in photography, 82

Neptune, discovery predicted by Leverrier, 61, 142 discovery by Galle, 61

Newcomb, fixes apex of solar motion, 222

Newton, law of gravitation, 212 longitude commission, 8

New York, its telegraphic time system, 120

Noon Signal, Washington, 120

Number, of nebulæ, 31, 33 of temporary stars, 38

Nutation, explained, 188