226 



lifting the cube a little or by immersing it in such a way that the 

 diagonal plane mentioned remains parallel with the liquid-level. 



A paper by Dr. Brandsen in which the resnlts described above 

 are set forth and proved is going to appear in the "Nieuw Archief 

 voor Wiskunde'". 



Petrography. — -'iJn somp rocks of the [shiml of Taliahu {Siila 

 Jsland.s.)" By Prof. Dr. A. Wichmann. 



(Gommnnicated in the meeting of May 30, 1914). 



After G. E. Rumphius had described, towards the end of thel7tli 

 century, some Jurassic fossils, originating from the east coast of 

 Taliabu ') it was not before the year 1899 that new geological inves- 

 tigations were made again in the island mentioned above. It was 

 R. D. M. Verbeek who collected some rocks in some places of the 

 Jiorth coast on the 4''' and 5''^ of August and afterwards described 

 them ■'). In November of the same year G. Boehm followed his 

 example, and chose as point of departure of his investigations the 

 findingplace mentioned by G. Rumphius, and afterwards continued 

 his work over part of the south coast') In December 1902, in 

 January and especially during the months of October and November 

 1904 an extensive part of the southern part of Taliabu was surveyed 

 l)y J. W. VAN NouHUYS ^). Tlie large collection gathered by him 

 was described by G. Boehm '"), in so far as regards the fossils. In 

 the following lines the communication of an investigation of the 

 rocks may find a place. 



1) D'Amboinscbe Rariteitkamer. Amsterdam 1705, p.p. 253 — 255. 



-) Voorloopig verslag over eene geologische reis door het Oostelijk gedeelte 

 van den Indischen Archipel in 1899. Batavia 1900, p.p. 9,10,46,47, — Molukken- 

 Verslag. Jaarboek van bet Mijnwezen van Ned. Indië. 37. 1908. Wetensch. ged. 

 Batavia 190S, p.p. 20-21, 107—108, 221—223. 



3) Aus den Molukken. Zeitscbr. d. D. geol. Ges. 54. 1902. p. 76. — Geologische 

 Milteilungen aus dem Indo-Australiscben Archipel. N. Jabrb. f. Min. Beil. Bd. 27 

 1906, p.p. 385 — 395. — Beilrage zur Geologie von Niederlandiscb-rndien. Palaeon- 

 tograpbica. Suppl. IV, Stuttgart. 1904, p.p. 6, 13—14. 



^) Maatschappij ter bevordering van bet Natuurkundig Onderzoek der Neder- 

 landsche Koloniën Bulletin No. 48. 1905. — Bijdrage tot de kennis van bet eiland 

 Taliaboe der Soela-groep (Molukscbe Zee). Tijdscbr K. Nederl. Aardrijksk. Genootscb. 

 (2) 27. Leiden 1910, p.p. 945-976, 1173—1196. 



'") Beitrüge zur Geologie von Niederlandiscb Indien. Paiaeonlograpbica. Suppl. IV 

 1912, p.p. 123—177. 



