A HISTORY OF ESSEX 



TABLE I 



TABLE II 



TABLE III 

 Totals in 10 gallons 



( Clear rivers IO 



, I Heybridge canal 50 



Freshwater \ ,-, , -t , j i- 



Heybndge basin and ditches 270 



\. Weedy stagnant ponds I 73 



Mean for sea water including the estuaries . . 2060 



One great object I had in view was to trace the changes in passing 

 from freshwater conditions down to the sea. The density of the water 

 was therefore determined by observing the excess in weight of the 

 measure of 1,000 grains of fresh water, which is given in the upper 

 line of Table I. In preparing this table I made no distinction between 

 Essex, Suffolk or Kent ; and the results are derived from observations 

 made in the Crouch, Roche, Blackwater, Colne, Stour, Orwell, Aide, 

 Bentley and Medway. 



As will be seen from Table I. there is a most striking difference in 

 the character and number of the different animals as we proceed from 

 freshwater conditions to the open sea, but there are very few kinds 

 more numerous in this than where the water is less salt. On the 

 whole there are most in the somewhat sheltered estuaries, where the 



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