On the Anticlinal Line of the London and Hampshire Basins. 41 



About four hours afterwards on the same day I tried again on 

 the same part of the circle, viz. from 1° to 4°, for fifteen minutes, 

 and obtained a rate of 12^'4! per hour. The next day, from 5° 

 to 6°, for twenty minutes, the rate was only 4*^*38 per hour. 

 Several other similar results were obtained, with which I shall 

 not trouble you; but these, contrasted with the experiments 

 made with the leaden ball, in which no such irregularities were 

 ever observed, render it evident that the iron weight was deflected 

 by magnetic currents, and that it is utterly impossible to obtain 

 correct results in these experiments when the pendulum-bob is 

 made of that metal*. ''^^ ■>/'- 



I am, Gentlemen, 

 ,; luxl 4ii / Yours very respectfully; ^'^^ ^ 



""'■'•" ^;'-i -^-i^^'.. - Thomas G. Bunt. 



VII. On the Anticlinal Line of the London and Hampshire 

 Basins. By P. J. Martin, Esq. 

 To Richard Taylor, Esq. 

 My dear Sir, , Pulborough, May 26, 1851. 



THE renewed interest which geologists take in the modus 

 operandi of the great chalk denudation of the Weald since 

 the advancement of Sir Roderick Murchison^s paper, read to the 

 Geological Society on the 14th instant, inclines me to request 

 that you would lend me your assistance for the promulgation of 

 some thoughts on the same subject, and for the description of 

 some additional natural appearances strongly illustrative, as I 

 think, of that phsenomenon. 



So long ago as the year 1828 you did me the honour to review 

 my first publication (see vol. iv. New Series, Phil. Mag.), in 

 which, as an appendage to a memoir descriptive of Western Sussex, 

 and taking the geological structure of that district as a type of 

 the whole, I ventured to bring forward a " Theory of Disruption 

 and Denudation" as a corollary to Dr. Buckland^s paper on 

 '^'^^ Valleys of Elevation," published in the Geological Transactions 

 of the foregoing year. The year following (in 1829) you also 

 published a paper in which, as further illustrative of the subject, 

 I made an attempt to restore the lost beds on the dome of the 

 Weald ; showing that, but for the instrumentality of the con- 

 comitant flood, the upburst of the Wealden would have produced 

 an elevation of at least four or five thousand feet, instead of an 

 excavation of as many hundred, above the sea-level. In a manner, 

 therefore, by an approximate synthesis as well as analysis, we 

 were led to the conclusion that the idea first broached by Dr. 

 Buckland in the before-mentioned paper was the correct one ; 



* A Postscript to this paper will be found at p. 81. 



