446 PKIZE QUESTIONS OF SCIENTIFIC SOCIETIES. 



Gothland, but such origin appears little reconcileable with the direc- 

 tion in which this diluvium is disposed, a direction which would rather 

 indicate a translation 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 fossils of the silurian and 

 other formations of that part of Norway, regard being at the same 

 time had to the modifications to which the translation from a remote 

 country and its consequences have subjected these minerals and 

 fossils. 



25. The combustion of steel, iron, and other metals, in oxygen, 

 is accompanied by the appearance of a multitude of incandescent 

 particles, which are thrown oQ" from the surface of the body in 

 combustion, and may be found after the phenomenon in the bottom 

 of the vessel in which the combustion is eflected. The same fact 

 is observed in the luminous electric arch of a strong battery between 

 two metallic rheophores, especially if these, or even one of them, is 

 of iron or steel. The society requests an explanation founded on 

 new and decisive researches of the cause of this phenomenon. 



The usual prize for a satisfactory answer to each of these questions 

 is a gold medal of the value of 150 florins, and a further donation of 

 150 Dutch ilorins, if the answer is thought to merit it. The answers, 

 legibly written in Dutch, French, English, Italian, Latin, or German, 

 (in Italic letters,) must be addressed free, with tickets after the man- 

 ner in use, to M. J. G. S. Van Breda, perpetual secretary of the 

 society, at Harlem. 



PROGRAMME OF THE BATAVIAN SOCIETY OF EXPERIMENTAL PHILOSOPHY AT 



ROTTERDAM. 



1. Question 105. It is desirable to obtain accurate statistical data 

 in reference to our drained marsh districts, and this society having 

 determined to continue its efforts, which have already been so suc- 

 cessful in reference to South Holland, has resolved to propose the 

 following question; 



"What are the statistical characteristics of one of the drained 

 marsh districts of our country." 



The reply to this question should give an account of the situation, 

 the figure, and the extent of this d^^ke district ; the elevation of the 

 surface compared with the plane of the level passing through the 

 zero of the scale of the plane of Amsterdam ; the separation of 

 the district into dykes, da^ms, or other hydraulic divisions, having 

 different summer levels; a succinct description of the windmills or 

 other apparatus in use .for pumping up and discharging the super- 

 abundant waters ; such description also giving the volume of the 

 water raised and the measure of its elevation ; the indication 

 of the changes successively made in these machines to increase their 

 discharging power, and the effect obtained, both as to the volume of 

 the water and as to the measure of its elevation ; the description of 



