Corrections in Vlacq's Tables of Logarithms. 353 



freshwater valley. Every thing denotes that their beds were 

 gradually heightened by the deposition of a marine sediment. 

 In this there is nothing remarkable ; the operation is daily 

 o-omg on on the Lincolnshire coast, where instances are re- 

 fatecf of the precipitation of a stratum of mud an inch thick, 

 in a sino-le day. The industry of man enables him to avail 

 himself of this tendency ;— the operations of nature are assisted 

 by art, and large tracts of the richest land have been artifi- 

 cially produced from the earthy materials brought by the 

 waters of the ocean. Had we need to travel further than the 

 adjoining county, this article might be extended by reciting 

 remarkable illustrations of the formation of alluvial lands, in 

 the numerous and fertile Danish islands of the Baltic ; in the 

 marsches on the coast of Sleswick, or in the Deltas on the 

 shores of the Adriatic. A due examination into all the facts 

 by which local changes are accompHshed,— whether in the gra- 

 dual absorption of high lands, on the one hand, or in the pro- 

 gressive emersion of extensive flats, on the other, — in either 

 case the result of existing causes, has always ended in con- 

 firming the general principle of the permanent residence of 

 the sea at one level, and without dimmution, since the deluge. 

 All the apparent exceptions are referable to local and existing 

 causes ; as in the cases of coral reefs, of muddy depositions, or 

 volcanic agency, which affect not the surface of the ocean, but 

 elevate or depress the base upon which its waters repose. The 

 balance of these fluctuations leaves the water level where it 

 ever stood : or if any alteration could be perceptible oyer so 

 extensive an area, it would be an elevation corresponding to 

 the disintegration of the land. 



[To be continued.] 



LXX. Corrections in Vlacq's Tables of Logarithms. 



To the Editors of the Philosophical Magazine and Annals of 

 Philosophy. 

 Gentlemen, 



THE importance of having our tables of logarithms accu- 

 rately printed, makes us greatly indebted to such men as 

 Mr. Babbage, when they will undertake the tedious labour of 

 minutely examining and correcting them. The same reason 

 induces me to submit to you a few observations on the list of 

 corrections, which are enumerated in page 300 of your present 

 volume. 



Every one knows the disgraceful carelessness with which 

 New Series. Vol. I. No. 5. Mat/ 1827. 2 Z Vlacq's 



