ON ROTATION OF CROPS. 185 



has the advantage of draining the surrounding country, 

 and of favoring the production of aquatic plants, which 

 afford food for a prodigious quantity of worms and insects. 

 All these productions, whether animal or vegetable, leave 

 their relics at the bottom of the sheet of water ; and, when 

 it is drawn off, the land remains covered with an abun- 

 dant stock of the richest manure. There are many ponds 

 of this description in the country of Bresse in the Lyonis. 

 If the water with which these parts abound were more 

 generally diffused, they would become marshy and un- 

 wholesome ; for it is the scum of superficial stagnant 

 waters which is deleterious, not the evaporation of deep 

 waters. On the other hand, were these ponds perma- 

 nent, their disposition of rich manure would either be lost, 

 or could be drawn out only at a great expense ; whilst, if 

 you change the locality of these ponds, by drawing off 

 the water to another spot, the manure remains ready 

 spread on the soil, and the farmer has only to plough it 

 in and sow his seed. The water in the mean time occu- 

 pies another low land, where, in its turn, it accumulates 

 and deposites its riches : with the assistance of locks, it 

 is thus made to perambulate through the valleys and low 

 lands. Great care is taken to preserve the young fish, 

 and transfer them to their new basins ; for these, like 

 the sheep of the meadow, not only supply us with food, 

 but enrich the soil for future vegetable produce. 



I was once present at the operation of drawing off a 

 sheet of water, of no less than seven hundred acres in ex- 

 tent. It was in the month of October. During the pre- 

 ceding summer, fish had been caught and wild fowl kill- 

 ed in prodigious abundance ; but when the secrets of the 

 prison-house were exposed to view, it afforded a very 

 curious spectacle. The markets of all the neighborhood 

 were supplied with full grown fish ; the young fry were 

 sold to stock other ponds ; and rich and ample were the 

 remnants of animal and vegetable manure which prepared 

 the ground for culture the following season. 



Simultaneous assolements are as advantageous to warm 

 countries as successive assolements are in our northern cli- 



1018. Where are many ponds of this description'? 1019. Under 

 what circumstances would they become unwholesome, and when would 

 the manure furnished by them be lost! 1020. How is the locality of 

 these ponds sometimes changed! 1021. What account does Mrs, B. 

 give of one of these operations! 

 16* 



