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VI. THE JUNTA DOS MATHEMATICOS.

, Advisory Committees.

King John II. is known, on several occasions, to have
referred questions of a scientific or technical nature to
men of learning who enjoyed his confidence and who
he believed would wisely advise him. He did so when
Columbus urged him to send an expedition across the
Ocean Sea in search of Cypangu and the East Indies.1
On that occasion the members of this Junta—to employ a
designation used not quite logically in connection with
such ephemeral committees—were Dr. Diego Ortiz de
Vilhegas, a native of Calzadinha in Leon, who had come
to Portugal in 1476, as spiritual director of that "most
excellent lady," D. Joanna, and stood high in the Royal
favour2; Dr. Rodrigo of Pedras negras, the chief
physician of the King, with whom his influence was
considerable, as we learn from the ' Epistola' of Cataldo
de Aquila, printed at Lisbon in 1500 ; and Master Josepe
or Jose, a Jew, who is undoubtedly identical with Jose
Vizinho, a pupil of the famous astronomer Rabbi Abraham
ben Samuel Zacut of Salamanca, Professor of Astronomy
and Mathematics in the University of his native town,
until 1492, when with thousands of his co-religionists he
fled Spain, and found a refuge in Portugal, where King
John appointed him Astronomer Royal.3 This Rabbi
Abraham is the author of an ' Almanach perpetuum
Celestium moduum cujus radix est 1473,' a work originally
written in Hebrew, but translated into Latin by
Jose Vizinho ' discipulum ejus,' and printed at Leiria in
1496.

A few years afterwards D. Diogo Ortiz, Dr. Rodrigo
and a Jew, Moyses, were instructed to prepare a map for
the guidance of Joao Pero de Covilha and Affonso de
Paiva, whom the King was about to dispatch in search of
the country of Prester John.4

It is, however, another 'Junta dos mathematicos'
which more especially interests us. This Junta was
appointed in 1484 or at latest in 1485. Its task was to
lay down simple rules for determining the latitude from
meridian altitudes of the sun, for the pole star, which had
served for that purpose in the past, was no longer available
once the Portuguese navigators had crossed the
Equator.

1 Barros, ' Da Asia,' Dec. I., liv. III., c. 11.

1 He became in succession Bishop of Tanger (1491), Ceuta (1500), and
Vizeu (1505), and as Grand Chaplain stood at the deathbed of King
John, together with Dr. Rodrigo. He died in 1519 (Paiva Manso,
' Historia ecclesiastica,' Lisbon, 1872, t, pp. 49, 62 ; Resende, c. 213).

3 On June 9, 1493, be was paid 10 golden espadins (about £7 10s.)
by order of King John, and signed the receipt in Hebrew characters, not
being permitted, as a Jew, to make us"} of the letters of Holy Writ (Sousa
Viterbo, ' Trabalhos nauticos,' I., 326).

* F. Alvarez, ' Verdadeira informacio,' c. 103 ; Castanheda, ' Historia,'
liv. I., c. 1. Father Alvarez was the chaplain and historian of a Portuguese
mission to Abyssinia, 1520-7. A translation of his narrative by Lord
Stanley of Alderley was published by the Hakluyt Society in 1881.

12 —

Joao de Barros and the 1 Junta.''

We are indebted to the famous historian Joao de
Barros6 for an account of this Junta. He mentions
Behaim as a member of it, and to him alone all later
historians—including G. P. Maffei,6 Petrus Matthaeus
(1590), Olfert Dapper,7 A. Cordeiro, S.J. (1641), andManoel
Telles da Silva (1689)8—are indebted for this information,
and there is thus no accumulative evidence as suggested
by several of Behaim's biographers.

J. de Barros (who wrote in 1539), having informed his
readers that when Vasco da Gama reached the Bay of St.
Helena he set up his large wooden astrolabe on land, as
he had been unable to obtain trustworthy meridian
altitudes of the sun on the deck of an unsteady vessel,
either with that instrument or with some of the smaller
astrolabes of brass with which he had been supplied, and
having asserted that the Portuguese mariners were the
first to employ these altitudes for the determination of
latitude, continues as follows :—

" At the time when Prince Henry began the exploration
of Guinea the mariners sailed within sight of the
coast, being guided by landmarks which they described
in sailing directions, such as are still in some way in use
at present, and this sufficed for this mode of exploration.
But subsequently, when, in the pursuit of their discoveries,
they lost sight of the land and penetrated the open sea,
they found that owing to currents and other secrets of the
sea their estimate of a day's work was frequently erroneous,
whilst an observation of the altitude (of the sun) would
have shown correctly the distance run. And as necessity
is the mistress of all arts, King John II. referred this •
matter to Master Rodrigo and Master Josepe, a Jew, and
both his physicians, and to one Martin of Bohemia, a
native of that country, who boasted of being a disciple of
John of Monte Regio, famed among the students of the
science of astronomy. These discovered this manner of
navigating by altitudes of the sun, and made tables of its
declination, such as are now in use among navigators, and
which are now more exact than in the beginning, when
these large wooden astrolabes were in use."

A statement made by so distinguished an author is
entitled to respect and deserves careful examination.
Still, I may be forgiven for directing attention to the fact
that even in the days of Prince Henry the Portuguese
were not afraid to venture upon the high sea, for they
sailed to the Azores, lying 600 sea miles from the nearest
land. Long before them the hardy Northmen, guided
solely by the stars and the flight of birds, had found their
way across the northern Atlantic, and Columbus would

6 'Da Asia,' Dec. I., liv. iv., c. 2.

• G. P. Maffei, S.J., was born at Bergamo in 1536 and died at
Lisbon, 1603.

' Olfert Dapper published a number of geographical compilations of
value between 1667 and 1688. He died (at Amsterdam) 1690.

8 ' De rebus gestis Joanni II.,' Lisbon, 1689. Telles da Silva, Marquis
de Alegrete, died 1709.