PEIZE QUESTIONS OF SCIENTIFIC SOCIETIES. 437 



Pleiades observed during the last revolution of the node of the 

 lunar orbit. 



3. The celebrated mechanist Ruhmkorff has obtained electric 

 sparks of extraordinary length by the induction apparatus which bear 

 his name. The society desires a determination, by both theoretical 

 and experimental researches, of the laws which govern the length 

 and the intensity of the sparks from instruments of different sizes and 

 construction, 



4. What difference is there in the perception of sounds with both 

 ears or with only one ? The society desires precise researches upon 

 this difference, and generally upon the influence of duality on the 

 organ of hearing. 



5. According to Pasteur, and other savans, fermentation is owing 

 to the development of cryptogamia and infusoria. The society re- 

 quests new and positive researches on this subject, with the addition, 

 if practicable, of an exact description of these plants and animals, 

 and of their mode of action. 



6. What is the best construction, and what the best mode of using 

 steamboats intendino: to clear rivers of the masses of ice which 

 obstruct their water-course? The society desires that those who 

 reply to this question will carefully consider all that practice has 

 already determined both in this country and elsewhere. 



7. The electric perturbations of the atmosphere give rise to elec- 

 tric currents in the telegraph wires. Notwithstanding all that recent 

 researches have made known, these phenomena are not yet completely 

 understood, and the society desires communications of the results of 

 numerous observations, with an account of the most remarkable con- 

 sequences which may be deduced concerning these currents and their 

 modifications according to the different causes producing them. 



8. With the exception of some sites on the eastern frontier of the 

 king«dom of Holland, the geological formations which are covered by 

 alluvial and diluvial deposits in this country are but very little known. 

 The society wishes to receive an account of all that excavations in 

 various places, and other observations, have ascertained with cer- 

 tainty of the nature of these formations. 



9. It is known, especially from the work of Professor Roemer, of 

 Breslau, that many of the fossils which are found near Groningen 

 belong to the same species as those which are found in the silurian 

 formations in the island of Gothland. This fact has led M. Roemer 

 to conclude that the diluvium of Groningen has been transported 

 from the island of Gothland; but that origin does not seem to be 

 reconcilable with the direction in which the diluvium is deposited, 

 which direction rather indicates transportation from the southern part 

 of Norway. The society suggests a decision of this question by an 

 exact comparison of the fossils of Groningen with the minerals and 

 the fossils of the silurian and other formations in that part of Nor^Yay, 

 regard being had to the modifications these minerals and fossils 

 must necessarily have experienced from distant transportation and its 

 consequences. 



10. The combustion of steel, iron, and other metals in ox^^gen, is 



