PRIZE QUESTIONS OF SCIENTIFIC SOCIETIES. 431 



nation of the laws of these phenomena; and it also desires a decision 

 of the question whether they are to be attributed to a certain mag- 

 netic inertia of the iron, or to the action of currents of induction, or, 

 perchance, to both of these causes at once. 



2. We require experimental researches upon the physical and 

 chemical properties of at least two species of vapor, subjected at 

 once to a pressure of at least a hundred atmospheres, and to a very 

 high temperature. 



3. Since the establishment of railroads, the construction of oblique 

 arches has very much increased. Nevertheless, the rules for fixing 

 the dimensions of these arches, and of their straight or sloping parts, 

 have not yet reached the degree of perfection arrived at in relation 

 to straight arches. The society, consequently, calls for a mathemat- 

 ical theory of oblique arches whence rules may be deduced for the 

 form and dimensions of these arches for their slopes, and especially 

 for the limit of the inclination allowable to such works. 



4. The origin of the sands which extend from the north of Bel- 

 gium into the Netherlands is not yet well ascertained. The society 

 requests a monograph of those sands; and it especially desires that 

 the rocks of which they are the detritus be indicated with exactitude, 

 if they exist upon the surface of the soil. 



5. Some geologists have expressed doubts as to the correctness of 

 the theory of the upheaval of mountains, which they are inclined to 

 attribute to the irregular sinking down of the surface, and the conse- 

 quent lateral pressure upon the contiguous strata. The society de- 

 sires an examination of some chain of mountains hitherto regarded 

 as having arisen solely as claimed by the long-received theory and 

 from no other cause, with a view to determine whether its form and 

 elevation must be explained by that cause, or whether they can be 

 sufficiently accounted for by a sinking and its effects in lateral pressure 

 and overlapping. 



6. Of what nature is the earth laid bare by the dr^'ing up of the 

 lake of Harlem, what is its chemical constitution, and what are we 

 to expect, as regards its fertility, from its chemical constitution and 

 physical properties ? 



7. The cause of the scratches and furrows to be seen in hard rocks 

 is commonly referred to the existence of vast glaciers in earlier geolo- 

 gical periods; the stones carried along by these glaciers having 

 grooved and channelled these rocks. Although as to many places 

 this explanation can scarcely be gainsayed, yet it must be confessed 

 that there are very many other places in which it may be safely af- 

 firmed that these effects have had other causes. We want an exam- 

 ination of the characteristics by which such causes may be marked 

 and accurately distinguished from the cause previously mentioned. 



8. The North sea has undergone changes from causes common to 

 all seas, as well as from local causes; as, for instance, like that of 

 the change in breadth of the Strait of Dover. The society desires 

 a knowledge of these phenomena, with their effects upon the con- 

 formation of the coasts, and especially upon the adjoining downs. 

 The society consequently inquires, what changes have been ob- 



