276 On Salt Marsh. 



part of the ground." Mr. Livingston has lately made 

 experiments that sanction the remark. Leaving this fact 

 to the philosophers, I adopt it for the present purpose, and 

 how forcibly does it apply to salt marshes ? Sir John Prin- 

 gle, speaking of Zealand, says that " by the evaporation of 

 the water in which various plants and insects die and rot, 

 the atmosphere, during the latter part of summer and au- 

 tumn, is filled with moisture and with putrid and insa- 

 lutary vapours. A second but less obvious source of 

 humidity, is from the water under ground; which in 

 that country lies near the surface ; and as the soil is light, 

 the moisture easily transpires, and in summer loads the 

 air with vapour, even where no water is visible. An- 

 other cause of the humidity and corruption of the atmo- 

 sphere, is imperfect ventilation. There are no hills to di- 

 rect the wind in streams upon the lower ground ; hence 

 the air is apt to stagnate." A better description of our 

 salt marsh country could not be given ; though the re- 

 cent improvements have in a very great degree altered 

 the general state of health in their neighbourhood. Pro- 

 fessor Vince, of Cambridge, has ascertained to his satis- 

 faction, that the Mediterranean sea evaporates one- tenth 

 of an inch per diem in summer ; so that our salt marsh- 

 es have every chance of a great supply of fog from the 

 Atlantic, and dew from the land ; and perhaps one proof 

 of it is, that cattle left on salt water beaches do not re- 

 quire so much drink as those fed on upland. It is said 

 that they are supplied with the necessary moisture from 

 descending vapour. I return from this digression to state 

 an opinion, that the mud casually deposited by exuberant 

 tides, with the residuum of fog and dew, may so fertilize 

 the spungy surface of salt marsh, as to make it produce 



