Freiburger historische Bestände - digital

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through the agency of Behaim, they would not have
attracted any special attention. Jose Vizinho, the most
active scientific adviser of King John and of his successor
King Manuel, knew, as a matter of course, that the
' Almanach' of Zacuto, his former teacher, contained
tables which would enable an observer to compute readily
his latitudes from an observation of the meridian altitude
of the sun, which was not possible as long as only the
' Tables' of King Alfonso 1 of Castile were available.
This 'Almanach perpetuum celestium motuum,' having
been translated by Jose Vizinho from Hebrew into Latin,
was first printed at Leiria in 1496, but there is no doubt
that MS. copies, especially of the few tables of special
interest to mariners, existed long before that time.2 The
« Almanach' contains four " tabulae solis " for a cycle of
four years (1473-6), including three ordinary and one leap-
year, and a " Tabula declinationis solis ab equinoctiali."
The former give the sun's geocentric longitude for each
of the twelve signs of the Zodiac and for each day of each
year, whilst the latter gives the sun's declination corresponding
to these longitudes. This declination table differs
but slightly from a similar table included in the work of
King Alfonso. With the help of Zacuto's tables a latitude
would be computed as follows :—

April 10,1473. Meridian altitude of the sun, 1 gQ0

observer south of the sun.....I

Sun's longitude in the sign of the Ram (Tabulal 0gO gg<

solis)..........I

Corresponding declination......11° 24' N.

O I

50 0
90 0

Zenith distance . . . 40 0 S.
Declination.....11 24 N.

Latitude . . 28 36 S.

It is credibly reported that Zacuto instructed the
pilots who sailed in his time on voyages of discovery,3 and
there can be no doubt that his ' Almanach ' was in use in
the Fleets of Vasco da Gama, Cabral, Joao de Nova
and Albuquerque.4 Of course, they may have been

1 These ' Tables' were calculated by two Jewish astronomers, 1262-
1272, but only printed at Augsburg in 1488.

a I consulted the first edition at the Bibliotheque de Ste. Genevieve at
Paris. Other editions, amended and enlarged, were printed at Venice
(1498, 1499, 1500 and 1502). The 1 Ephemerides sive Almanach perpetuum
,' edited by Johan Lucilius Santritter of Heilbronn, and printed
by P. Lichtenstein at Venice in 1498, are described by R. Wolf
(' Geschichte der Astronomic,' p. 97) as the work of Regiomontanus, when
in reality they are by Zacuto, of whose existence he seems to have been
unaware.

3 Gaspar Correa, ' Lendas da India,' I. (Lisbon 1858), pp. 10, 16, 23,
261-4, 375. Correa went out to India in 1512 and died there before
1583. His ' Lendas' deal with the history of India up to 1550. They
were partly written in 1561 and are of varying trustworthiness.

4 Vasco da Gama sailed for India in 1497 and 1502, Cabral in 1550,
Joio da Nova in 1501, Affonso de Albuquerque in 1503.

supplied as well with the ' Ephemerides' of Regiomontanus
, and we know that Columbus and Vespucci made
use of the work of the great German astronomer.
Andres de San Martin, one of the pilots in Magellan's
fleet, who was killed in Sebu in 1521, had both the
' Almanach' of Zacuto and the ' Ephemerides,' and
found both woefully in error when attempting to calculate
a longitude from a conjunction of Jupiter and
the moon, which he had observed on December 17,
1519.6

. Francisco Albo, another pilot of Magellan's expedition,
who was fortunate enough to return to Spain, to judge
from the log-book as published by Navarrete (IV., 1837,
p. 209), evidently had tables of declination of our modern
type.6 These tables are entered with the date, and furnish
the sun's declination at a glance, without the computer being
obliged to have recourse to a " Tabula Solis " giving the
sun's geocentric longitude. Eugen Gelcich7 surmises that
" tables were prepared in this form at the suggestion of
Behaim and of his colleagues of the Junta, in order to
meet the requirements of mariners." Jose' Vizinho might,
of course, have prepared such tables, and so might any
ordinary pilot, for their computation called for little
skill and no knowledge of astronomy. But I demur even
to the suggestion that Behaim, whose ignorance of nautical
matters 1 believe to have been proved, had a share in this
humble work.

The earliest printed tables of this kind I found in
Martin Fernandez de Enciso's 1 Suma de Geographia'
(Seville, 1519). These tables, like all those of a subsequent
date, are calculated for a cycle of three ordinary and one
leap year, as in Zacuto's ' Almanach.' Two sets of
similar tables are found in a MS. Codex now in the library
of the Duke of Palmella, and published at his expense.8
This codex contains a treatise on the mariner's compass
by Joao de Lisboa,9 dated 1514, besides a number of other
papers and documents by unknown authors dating from
the end of the fifteenth to the middle of the sixteenth
century. Among these are two sets of declination tables,
the one of the usual type, the other peculiar, inasmuch
as the point of reference for what its author called
" declination" is the North Pole. Thus decl. 23° S. is
expressed by 90° 4-23°= 113°, whilst decl. 23° N. is given
as 90°-23° = 67°. Neither date nor author of these two
sets of tables is given. The last set of tables which need
be mentioned are printed in Pedro de Medina's ' Arte de
Navigar' (Valladolid, 1545).

The fact that these various tables were computed

8 Herrera, Dec. II., lib. IV., c. 10.

6 The tables quoted by him differ from those of Enciso to the extent
of one to three minutes.

' 'Die Instr. u. d. wissensch. Hiilfsmittel der Nautik' (Hamburg,
Festschrift, 1892), p. 90.

8 ' Livro de Marinharia, cop. e coordenado por Jacinto Ignaccio de
Brito Rebello' (Lisbon, 1903).

9 Joao de Lisboa accompanied Tristao da Cunha to India in 1506, was
appointed Kioto mor in 1525, and died in 1526.

D 2