OP WATERING PLANTS. 145 



may be planted with trees, the roots of which will help 

 to keep it together, and the evaporation by the leaves 

 will assist in draining it ; but care must be taken to thin 

 the branches, in order to give free access to the sun and 

 wind ; nor must they be allowed to grow high, lest the 

 wind, having too great hold of them, should loosen the 

 roots, and thus injure, instead of preserve, the dyke. On 

 the side next the ditch it is advisable to plant reeds. 



Emily. But how are you to get rid of the water which 

 fills the ditches ? 



Mrs. B. That depends, in a great measure, upon the 

 locality: it must be carried off to the nearest running 

 water, or to the sea ; without a resource of this kind, it 

 would be vain to attempt to drain a marsh. If we can 

 succeed in preventing the external waters from gaining 

 admittance, that which the marsh contains is so soon 

 dried up by evaporation, that care must be taken not to 

 overshoot the mark, and leave an insufficiency of mois- 

 ture for the purpose of cultivation. 



Caroline. Some attempts of this kind appear to have 

 been made towards draining the Pontine marshes ; a ca- 

 nal of water borders each side of the road, which is 

 flanked by a bank of earth planted with trees ; and when 

 we passed, I saw, with regret, that they were cutting 

 most of them down. 



Mrs. B. It was probably found, that more injury was 

 produced by their shade, than benefit derived from the 

 evaporation of their leaves. But this attempt at draining 

 the Pontine marshes is of a very circumscribed nature, and 

 attended with little success ; although the vicinity of the 

 sea affords facility for carrying off the water, the difficulty 

 of draining these marshes has never yet been surmounted. 



When marshes are situated below the level of the sea, 

 as is generally the case in Holland, to drain them is a 

 very laborious undertaking, and requires all the patient 

 persevering industry of the Dutch to accomplish. They 

 begin by making the water run off into canals, and then 

 raise it, by mechanical means, into more elevated chan- 

 nels, till it attains an elevation above the level of the sea. 



805. What is said of planting trees upon it 1 ? 806. How is the 

 water filling the ditches to be removed 1 ? 807. What is said of drain- 

 ing the Pontine marshes 1 808. How are the marshes of Holland sit- 

 uated! 809. How are they drained'? 



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