304 Prize Subjects proposed by the 
The manner the tide arranges the materials on a sea- 
beach may here be noted as connected with the source of 
sand-hills. Where the shore is sandy and free from pebbles, 
the sand at half-tide level is finer and less permeable to 
water than it is near high-water mark, with the specific 
gravity of the two nearly equal. Where the shore is com- 
posed of sand and stones, the former occupies the half-tide 
level, and a belt of pebbles the high-water ground. This 
effect of the waves throwing up the coarser part of the sand 
to the top of the tide is very marked on the coast of Den- 
bighshire, on the borders of the Irish Sea; also in Brodick 
ane in the Island of Arran. 
es, 
Prize Subjects proposed by the Society of Sciences at 
Harlem for the year 1856. 
The Dutch Society of Sciences resident at Harlem pro- 
posed a great number of prize subjects for competition in 
1854. Three questions only have been taken up by the com- 
petitors ; lst, That on the fossil vegetables of the chalk for- 
mations ; 2d, That on the air and water of the Low Countries | 
in the neighbourhood of the sea, of which the Society re- 
quired an examination in respect to the existence or non- 
existence of iodine; 3d, That on the spectrum of the elec- 
tric light, and the differences which the rays of Frauenhofer 
present when the luminous arc is formed between different 
metals. The last of these questions is the only one that 
has been treated in such a manner as to deserve the prize. 
The author of the memoir is M. Masson, Professor of 
Natural Philosophy in the Imperial Lyceum of Louis-le- 
Grand, at Paris. The society now proposes, for the compe- 
tition of 1856, the following prize subjects :— 
1. Some natural philosophers allege that apart of an electric 
current, passing along an electrolyte, traverses it without ex- 
ercising any chemical action. The society requires that this 
opinion should be submitted to a rigorous experimental ex- 
amination; and that, in case of it being found correct, the 
experimentalist should determine, at least in respect to six 
different electrolytes, the numerical relation existing be- 
tween the part of the current which decomposes the electro- _ 
