1600 : 
essigsauren Veratrins. Untersuchungen aus dem physiologischen Laboratorium 
in Wiirzburg, Theil I, 1867 Seite 73. 
3. K. Hepsom, Ueber die Einwirkung verschiedener Stoffe auf das isolierte 
Säugetierherz. Skandinav. Archiv f. Physiologie Bd. 8 und 9. 
4. K. Heppom, Beiträge zur Kenntniss der Wirkungen des Antiarins. Arch. für 
experim. Pathologie und Pharmakologie. Band 45. Seite 317. 
5. W. Srraus, Ueber die Wirkung des Antiarins am ausgeschnittenen suspen- 
dirten Froschherzen. Arch. für exper. Pathol. und Pharmakologie. Bd. 45. 
1901 Seite 346. 
6. S. pr Boer, On the heart-rhythm J, If and, [IL Koninklijke Akademie van 
Wetenschappen. Proceedings of the Meeting of Saturday February 27, March 
27 and April 23 1915 Vol. XVII and XVILL page 1075, 1185 and 84. 
7. S. DE Boer, Sur le rhythme du coeur. Archives Néerlandaises des Sciences 
exactes et naturelles série IIL B. Tome II p. 525—593. 
S. S. pe Boer, Rhythmiek en metabolism van de hartspier. Public lecture held 
at the opening of his lessons as a private-lecturer at the University of 
Amsterdam on 21 Oct. 1915. Nederl. Tijdschr. v. Geneeskunde Jrg. 1915 [Id 
half pag. 1927. 
Astronomy. — “Short account of some works by BENsAUDE upon 
the knowledge of astronomy and navigation in Portugal at 
the time of the great discoveries in the 15% and 16% centuries, 
presented to the Academy by the author.’ By Prof. H. G. van 
DE SANDE BAKHUYZEN. 
(Communicated at the meeting of March 25, 1916). 
During the 14 and 15 centuries, the Portuguese, as is well 
known, made a number of important voyages along the west coast 
of Africa. They had reached the Canary Isles before 1336, and 
their sea power is demonstrated by the conquest of Ceuta in 1415. 
In 1462 they undertook a voyage to Guinea, visited St. George del 
Mina in 1481, and some years later Joseph Vizinno accomplished a 
number of determinations of latitude in Guinea. In 1487—88 
BARTHELOMEU Diaz made his voyage to the Cape of Good Hope, and 
in 1497 Vasco pr Gama undertook his expedition to the Indies round 
the Cape. 
In some of their first voyages they probably kept pretty close to 
the shore, and made use of a few maps, and the compass. But 
when the voyages became more extended, astronomical determina- 
tions became necessary, and it was probably before 1483 that Juan 
II, to whom his father had entrusted the administration of the Por- 
tuguese colonies in 1474, although he did not succeed to the crown 
until 1477, called together a Commission or Junta, to examine into 
