1602 
the field of navigation, and published the resulfs of his investigations 
in a work entitled “1 Astronomie nautique au Portugal a l'époque 
des grandes découvertes”, (1912) to which later on he added the 
testimony of three photographie reproductions of very rare books 
published in Portugal. San 
In this book BeNsAvDE comes to the following conclusions. 
That Rrcgiomontanus cannot be regarded as the inventor of the 
astrolabe, a fact which many German writers readily acknowledge, 
is shown by the existence of several Arabian astrolabes from a much 
earlier date, amongst others, one in the Bibliotheque nationale in 
Paris dating from the year 950, which in its essential features 
corresponds to the astrolabes used in Portugal towards the end of 
the 15 century, and only differs slightly from those made in Nuremberg. 
As these astrolabes were used in Portugal for astrology, which, 
there as elsewhere, was much practised in the beginning of the 
15 century, there are no sufficient grounds for supposing that the 
knowledge of the arabian astrolabes should have been lost in Portugal, 
and that these instruments should have been re-introduced later 
from Nuremberg. As a matter of fact the astrolabe was used by 
Dingo D'AZAMBUJA as early as 1481 on his voyage to Guinea. 
Further Bensaupe deals with the tables which were used in 
Portugal to find the position of the sun, and in particular its 
distance from the celestial pole for each day. It is usually supposed 
that these were the tables given by Reciomontants in his “Ephemerides”. 
In these tables, however, are only found the longitude of the sun, 
and its place in the various signs of the zodiac and if from: this 
the distance of the sun from the celestial pole is to be derived, it 
must be done by means of formulae, a knowledge of which could 
certainly not be expected from the mariners on board those vessels. 
In another work “Tabulae direetionum” although ReEGIOMONTANUS 
gives the distance of the sun from the celestial pole, it is not for 
every day, but only for the different positions which the sun occupies 
in the zodiac, so that the mariner who only needs the distances 
from the pole for his determination of latitude, would still need 
to take both these books of Rearomonrants with him, which would 
be a somewhat elaborate method. 
Through his researches BeNsAupr has discovered a small Portuguese 
work, which is much more suitable for the use of mariners. It 
consists of two parts, 1. directions for the use of the astrolabe 
and quadrant, and 2. a treatise upon the celestial spheres. 
Of this work, a copy of which is to be found in the Munich 
library, Brnsaupg publishes a photographic reproduction, the title- 
