198 Mr. Robberds on the former Level of the German Ocean^ 

 been produced by any deficiency in the supply of water, either 

 from the main source, or tributary springs of theWensum ; for 

 all the mills situated upon it have continued their usual ope- 

 rations, nor has there been any perceptible abatement in the 

 strength of the current by which their machinery is set in mo- 

 tion. These facts evince that a progressive reduction in the 

 amount of the floods of this valley has been going on from the 

 date of the earliest records up to the present time. How then 

 has the former excess above the quantity of water now exist- 

 ing been carried away ? The mouth of the haven at Yar- 

 mouth is the only passage at which it can have flowed out; 

 and in order to effect this, the average outfall of the ebb at 

 that point during the last seven centuries must have been 

 greatei' than the influx of the rising tide. But I have already 

 shown that this could not have been the case, if the level of 

 the German Ocean remained unchanged; therefore, as it is 

 an indisputable fact that the receding tide has carried away 

 a greater body of water than it brought in during its access, 

 it necessarily follows that the floods which have left the val- 

 leys must have been drawn off" by the depression of the re- 

 servoir in which they have been absorbed. 



But Mr. Taylor maintains also that these floods have been 

 driven out by the growth of solid land occupying their place ; 

 that the tide has been excluded " from its ancient receptacles 

 by the gradual precipitation from waters charged with alluvial 

 mud." This argument rests upon an assumption, which is 

 physically impossible and logically absurd ; it supposes water 

 to have the power of forming deposits, not only even with, but 

 actually above its own surface ; which includes the pi'oposition 

 that a part is not only equal to, but greater than a whole. 

 The average of the specific gravities of all mineral bodies is 

 2'5 * ; therefore two cubic inches of earth are equal in weight 

 to five of water ; and supposing a body of water to be "charged 

 with alluvial mud " to the amount of one-fourth part of its own 

 weight, (which I consider to be a large allowance,) the volume 

 of the former would be to that of the latter as 5 x 1 to 2-r-4', or 

 as 10 to 1. Admitting still further, that these waters would 

 clear themselves of all their impurities at one point, their de- 

 posit must settle beneath a superincumbent fluid at least ten 

 times greater than itself. Each successive addition to a bed 

 of new land must be a residuum of this kind, and consequently 

 at the last stage of its completion the water which brought 

 together its materials must still have flowed above its surface. 

 To expel that water, therefore, by the precipitation of its own 

 mud, would be part of a progression which, if we can suppose 

 * Playfair's Illustrations of the Huttonian Theory, p. 492. 



