neteen years of observation before the discovery of
nutation could be announced: how seldom do these years of toil present
themselves to our imaginations when we glibly say that "Bradley discovered
nutation," or "Hencke discovered Astraea"! That the necessary labour is so
often forgotten must be my excuse for recalling attention to it somewhat
persistently in these examples.

But beyond the fact that he must work hard, it would seem as though there
were little of value to tell the would-be discoverer. The situation has
been well summarised by Jevons in his chapter on Induction in the
"Principles of Science;" and his words will form a fitting conclusion to
these chapters:--

"It would seem as if the mind of the great discoverer must combine
contradictory attributes. He must be fertile in theories and
hypotheses, and yet full of facts and precise results of experience.
He must entertain the feeblest analogies, and the merest guesses at
truth, and yet he must hold them as worthless till they are verified
in experiment. When there are any grounds of probability he must hold
tenaciously to an old opinion, and yet he must be prepared at any
moment to relinquish it when a clearly contradictory fact is
encountered."

INDEX

Aberration, 105-109, 111, 112, 117, 118, 185, 188, 192, 214, 215

Accidental discovery, 15, 73, 121-154

Adams, 12, 45-85;
resolution, 55

Airy, 32, 40-85, 214

Algiers, 130

Alleghenia, 26

Almucantar, 180, 181

Alphabet used for planets, 27

Anderson, Dr. T. C., 8, 142, 143, 144, 146

Anthelm, 142

Apollo, 9

Argon, 109

Ascension, 34

Assumption, forgotten, 196

Astraea, 22, 23, 219

Astrographic chart, 122, 125, 130

_Astronomical Journal_, 177-217

_Astronomische Nachrichten_, 52, 158

Astrophil, 143

Auwers, 142

Ball, Sir R., 24

Balliol College, 87

Banks, Sir J., 9

Barnard, E. E., 146, 220

Berlin, 181, 183, 184, 188, 193

Berlin star-map, 45, 66, 83, 124

Bessel, 192

Bettina, 26, 27

Birmingham, 142

"Black Drop" (in transit of Venus), 30

Bliss, 114

Board of Visitors of Greenwich Observatory, 63

Bode, 11, 14, 15, 22

Bode's Law, 12, 13, 38, 43, 45, 52, 72, 76, 77, 84

Bourdeaux, 130

Bouvard, 39, 40, 42, 48, 49, 50, 61

Bradley, 39, 86-120, 188-192, 213, 214, 218, 219

Bradley, John, 115

Bremen