ee 
Undulating or Hilly Ground. 301: 
Mr Miller’s gauges are distributed over 25 localities, in 
all of which the annual fall of rain greatly exceeds that of 
West Lancashire ; the mean depth shown by the 25, given in 
in his table, is ; i . 82-88 inches, 
From which deduct ‘cana fall at Liverpool 28:05 __,, 
54:83, 
the excess of rain due to hilly ground. A square of 25 
miles a side or 100 perimeter would inclose the chief portion 
of the district in question ; the yearly excess of water of 
54-83 inches deep, distributed over the area of the square, 
shows that the condensation of aqueous vapour amounts to 
252,852 tons weight per hour. If the 100 miles perimeter was 
made to inclose a circular area in lieu of a square one, the 
weight of water condensed per hour would be a little over } 
more. 
Sand Hills—The action of a stormy atmosphere on a flat 
sea-chafed sandy beach, has the effect of producing a belt of 
sand hills that in some degree exercise the influence of hilly or 
undulating ground in checking currents of wind. I wish to sub- 
mit the view I take of the formation of these hills, which, I 
trust, may prove of interest, seeing that the question of stay- 
ing the progress of sand is in some countries one which is 
studied with anxiety. On the shores of France, of Holland, 
and in this neighbourhood, grasses are cultivated for the pur- 
pose of binding the sand, and preventing it from damaging 
adjoining fields. And it has been argued that in Egypt the 
object the ancients had in rearing those masses of masonry, 
the Pyramids, was for a like purpose. 
In Liverpool bay the tide flows over extensive sand-banks, 
and beats on a smooth sandy shore; near the high-water 
line the sand is of a clear, sharp character, through which 
water percolates freely; specific gravity 2:58. I have re- 
peatedly noticed that a brisk wind playing on a bank of this 
kind, within two hours from the time it had been dried by 
the tide, detached particles of sand, which the wind carried 
along the surface of the ground in the form of light, fleecy- 
like clouds. When this process is extended through ages, 
the result of it is that a quantity of sand is lodged above 
