Freiburger historische Bestände - digital

I

Humboldt,1 Rudolf Wolf,2 and others. It is, however,
stated by Manuel Telles da Silva, Marques de Alegrete,3
that the astrolabe was made use of for the first time by
Diogo d'Azambuja in 1481, that is, several years before
Behaim arrived in Portugal.4

The Meteoroscope.

Sebastiao Francisco de Mendo Trigozo5 suggests that
Behaim merely made known in Portugal certain instruments
made in Nuremberg, and the ' Ephemerides' of
Regiomontanus. Among the instruments he mentions
the meteoroscope of Regiomontanus, an adaptation of a

The Meteoroscope.

similar instrument devised by Ptolemy, and described in a
letter to the learned Greek Cardinal Bessarion.6 Martin
Cortes,7 the son of the famous conqueror of Mexico,
explains how this instrument enables an observer to
determine the latitude and time by extra-meridian
altitudes of the sun. The " hemisphere nautique" invented
in 1581 by Michal Cognet of Antwerp, and
described by G. Fournier,8 is in reality nothing more than

1 ' Krit. Unters.,(Berlin,1874),p. 234, where he suggests that" Behaim's
aBtrolabe, which was hung up to the mast ( !), was perhaps only a simplified
adaptation of the meteoroscope of Regiomontanus."

» 'Geschichte der Astronomie' (Munich, 1877), p. 100.

3 ' De rebus gestis Joanni II.' (Lisbon, 1689), p. 152.

4 Diogo d'Azambuja was born in 1432 at Montemor, and died there
in 1518, having done valiant service in Africa and Asia. He was leader
of the expedition which built the Ciritella de S. Jorge da Mina (1481-4)
(L. Cordeiro, ' Diogo d'Azambuja,' Lisbon, 1892).

6 ' Memoria sobre Martim de Bohemia' (' Mem. de litt. portug.,'VIII.,
Lisbon, 1812, seg. ed., 1856, p. 371).

* Published by Schoener (Ingolstadt, 1533). Apianus, ' Instrument-
buch' (Ingolstadt, 1533), and Ghillany, p. 39.

7 ' Breve compendio de la Sphera' (Seville, 1556, III., c. 11).
9 ' Hydrographie' (Paris, 1643), liv. X., cc. 17, 18.

the upper half of the meteoroscope. Fournier, a very
good judge, looks upon this instrument as being
absolutely useless on board ship, as its orientation
depended upon a knowledge of the variation of the needle
when making an observation.

The Cross-Staff.

Dr. A. Breusing,9 director of the " Seefahrtschule " of
Bremen, was the first to suggest that the instrument made
known to the Portuguese by Behaim, was the cross-staff,
and Dr. S. Giinther10 agrees with him. The earliest
description of this instrument is by Levi ben Gerson, a
learned Jew of Banolas in Catalonia, and was dedicated
to Pope Clemens VI. in 1342." Levi calls his instrument
" baculus Jacob," George Purbach,12 " virga visoria," and
Regiomontanus, " radius astronomicus." The last has
frequently been credited with its invention, but J. Petz
has shown that he was acquainted with Levi's description
of it.13 Pedro Nunes,14 the famous Portuguese astronomer,
quotes Regiomontanus when describing the baculus
or radius astronomicus. Among Portuguese and Spanish
seamen it became known as balestilha, among Frenchmen

The Cross-Staff.

as arbalete, in England as cross-staff.15 It is a very
simple contrivance for observing stellar distances and the
altitudes of heavenly bodies. Our illustration sufficiently
shows its appearance and the manner of its use. It merely

9 ' Zeitschrift d. Ges. f. Erdkunde,' IV. (Berlin, 1869).

10 ' Martin Behaim ' (Bamberg, 1890), pp. 25, 63, and EnestrSm's 1 Bibl.
mathem.,' new series, IV., p. 77.

11 Levi ben Gerson died at Perpignan in 1370. His MS. is at Munich
(cod. lat. Mon., 8089. Its contents were first made known by S.
Gunther).

12 This famous astronomer was born at Peuerbach (Austria) in 1423.
He died 1462 as Professor of Mathematics at Vienna. Johan de Monte-
regio, or Regiomontanus, was his pupil.

13 'Mitt, des Ver. f. d. Geschichte Nurnberg's,' VII., p. 123.

u ' De arte atque ratione navigandi' (Coimbra, 1546), lib. I., c. 6,
which was originally printed as an appendix to a ' Tratado da esphera'
(Lisbon, 1537), or ' De regulis et instrumentis' ('Opera mathematical
Basel, 1566, p. 73).

15 Dr. Bittner ('The Mohit of Admiral Sidi AH ben Hosein, 1554,'
Vienna, 1867) suggests that "balestilha" may be derived from the Arabic
" al balista," altitude, and not from the Latin " balista." On the instrument
used by the India pilots for taking the altitudes of stars, see Barros, ' Da
Asia,' Dec. I., lib. IV., c. 6, and my ' Vasco da Gama,' p. 27.