16 Hart Street, Bloomsbury - Further to their conversation concerning CL's doctrine of 'uniformity' in his 'Principles of Geology', certain passages from the first edition have been unfairly seized upon by his critics and not fairly considered. CL believes that any reader of Adam Sedgwick's anniversary address to the Geological Society 'would suppose that I had contended for 'an indefinite succession of similar phenomena' [Address, p. 25]. And the suggestion by AS that he had not made due allowance for the creation of man. However, CL did claim in the first edition that this 'innovation' was 'a new cause differing in kind and energy from any operation' and mentioned it as an unanswerable objection against any one who was contending for absolute uniformity. p. 156'. CL's 'notion of uniformity in the existing causes of change always implied that they must forever produce an endless variety of effects, both in the animate and inanimate world'. He 'did not lay it down as an axiom that there cannot have been a succession of paroxysms and crises on which 'a priori reasoning' I was accused of proceeding, but I argued that other geologists have usually proceeded on an arbitrary hypothesis of paroxysms and the intensity of geological forces, without feeling that by this assumption they pledged themselves to the opinion that ordinary forces and time could never explain geological phenomena'. There is a traditional prejudicial emphasis in geology 'that in attempting to interpret geological phenomena the bias has always been on the wrong side, there has always been a disposition to reason a priori on the extraordinary violence and suddenness of changes both in the inorganic crust of the earth and in organic types, instead of attempting strenuously to frame theories in accordance with the ordinary operations of nature'. WW should read what AS has to say on the two different methods of theorising in Geology and what he says in his address for 1831 of De Beaumont's system of parallel elevations and CL's chapter on the same subject: 'De Beaumont's system was properly selected by him as directly opposed to my fundamental principles...It was a theory invented not only without any respect to the reconciling geological events with the ordinary course of changes now in progress but it evinced at every step that partial leaning to a belief in the difference of the ancient causes and operations which characterises the system of my opponents'. AS was 'prompted by the same theoretical bias which assumes the discordance between the former and existing course of terrestrial change...I know not how much of De Beaumont's theory Sedgwick now believes, probably but a small part of it'. AS 'considered that my mode of explaining geological phenomena, or my bias towards a leading doctrine of the Huttonian hypothesis, had served like a false horizon in astronomy - to vitiate the results of my observations - But has he not himself been unconsciously warped by his own method of philosophizing which he has truly stated to be directly at variance with mine!' CL gives a detailed answer to AS's critique of his work. If CL had plainly stated as Herschel had done in his letter to CL regarding the 'possibility of the introduction - or origination of fresh species being a natural in contradistinction to a miraculous process I should have raised a host of prejudices against me which are unfortunately opposed at every step to any philosopher who attempts to address the public on these mysterious subjects'. CL attempts to distinguish between a Uniformitarian and the Catastrophist by an imaginary case by appealing to WW's work in tides and a hypothetical case. 'The difficulty which men have of conceiving the aggregate effects of causes which have operated throughout millions of years far exceeds all other sources of prejudice in Geology and is yet the most unphilosophical of all'.