Agricultural Meteorology. 
333 
Paris was 18 38 inches; duiinjj the last forty j ears the average 
has been gradually increasing : it is now 20* 86 inches. 
At Milan, from 17G3 to the present time, the records of 
meteorology show an increase from 36 "81 inches to 40 '66 inches. 
At La Rochelle the average from 1777 to 1834 was 28-11 
inches; from 1833 to 1840 it has been 28 '87 inches. 
In the valley of the Rhone, according to Flauguergues, the 
mean of decennial periods has been as follows: 1787, 33*14 
inches; 1797, 35-39 inches; 1807, 36-45 inches; 1817, 40-66 
inches. 
These figures all point the same way, and indicate a tendency 
to increase from the shores of the Bay of Biscay to the centre of 
Europe. Can it have been from a change in the character of the 
rains, their diffusion over a greater length of period in falling 
and through a greater number of days ? For a constant suc- 
cession of heavy showers, falling closely one after the other, 
supplies a greater quantity of water to streams and rivers than 
when the same quantity falls in the course of many days, separated 
from each other by dry intervals ; for the land has then time to 
dry and can absorb the moisture, which comes gently down, 
without permitting it to run off the surface. 
The effects of Enclosure Acts in this country certainly tend to 
alter the conditions of our rivers, and those effects will be still 
further increased by the operations of agricultural drainage, now 
so generally proceeding throughout the country. In both cases 
the result has been the rapid delivery of a large quantity of 
water, which formerly remained stagnant in the ground till 
evaporated by the summer heats, slowly draining off meantime 
from below into the rivulets to which they acted as natural reser- 
voirs — springs from which a slight supply continued to be afforded 
till the autumn. During the height of agricultural enterprise in 
the war-time the enclosure of commons became very frequent ; 
and though draining was not systematically practised, yet the 
mere fencing and division into fields of 10 or 15 acres by means 
of hedges and ditches did, as far as their influence reached, 
effectually draw off a large quantity of what would otherwise 
have remained much later in the soil. Many streams in conse- 
quence, which used to flow during the whole summer, are now 
dry before the middle of May. The annual volume of water 
carried down by our rivers to the sea may be the same as before ; 
but the effect of the drainage, when complete, will be to alter 
the times in which that volume is to be conveyed ; it will be less 
evenly diffused, the contributions will arrive more hastily and in 
larger quantities within short given periods than formerly. It is 
now commonly said in praise of the improvement and as a proof 
of the skill and success with which it has been carried out, that 
