176 Mr. Smith's Geological Claims stated, 



valleys being found, where several of the others come to the 

 surface. And having then fully adopted and practised this new 

 p^'inciple of selection, (or chooaing such of the strata, out of the 

 great number of others, as should first have colours assigned 

 them, and the tracing and depicting of tthich on his Map, should 

 lejirst attempted. 



5th. Having made use of certain Strata selected as t^bove (se- 

 veral of which are very unimportant in almost any other point 

 of view, but their visible edges, and had not even received a 

 name, or been mentioned in previous geological writings) as the 

 subsequent means of mapping or filling i?i, between ihera?iges of 

 these characteristic Strata, as many of the less conspicuous (al- 

 though perhaps more useful) strata*, as tb.e scale of the map 

 would admit; a practice quite new among<^t the makers of mi- 

 neral Maps, of mine or colliery Estates, then, or ever, now, ex- 

 cept by those who have expressly followed Mr. Smith in this 

 practice. 



6th. Having in these early parts of his Survey of the strata of 

 England, l)y that very particular attention to the nature of the 

 .surface Soil, and its fitness for and appropriation to particular 

 kinds of vegetable cultivation or spontaneous growth, which his 

 previous and early habits as a Land-survej-or and Valuer, had led 

 and enabled him to pay to these objects, while investigating the 

 strata beneath ; succeeded, in ascertaining and establishing nn- 

 aieroiis helps to the mineral surveyor, from the visible appear- 

 ances of the Fegetal'le productions of a district, towards tracing 

 out the surfaces of its less conspicuous Strata beneath f . 



7ih. 



* In all the numerous and wide-spread opportunities which Mr. Smith, 

 Mr. Farey, and other of his friends have had, in seeing tlie mnp.i which are 

 in }he possession of the mineral Owners, and their Lessees and Agenls, and 

 in those of professional Coal-viewers, &c. throughout Great Britain, not an 

 instance has occurred, of any of these maps depicting the thick Rocks fnd 

 Strata, ivhouc cdgca are consplcnons on the surface, as the means of niarkiiig 

 out, almost paraltjl strips, iviflihiwlitclt ticc coals, irorisiones, thin limex'ri:i':.i, 

 fire-clay, &c. &c. are to be found ranging; although, in all the minut'ia? of 

 surveying mineral estates, these principles and proceedings of Mr. J^. aie 

 equally, and even more applicable and useful, than they are in kingdom, 

 county or district surveys. As a recent instance may here be quoted, the 

 survey of the Leinster coal district in the South of Ireland, made by Mr. 

 Richard Grithth junior, in ISM, and since published by the Dublin Society; 

 wherein, tite bassets of no rocks are attempted to be shown, wit'iin the coal- 

 field, but merely the basset ring of one coal-seam, and broken part.-; of t!ie 

 bas.sets of three others ; the ascertainment of which coal-bassets, must liavc 

 been as laborious as the accurately marking out of half, or perluips the 

 whole of the basset-edges of the principal sandstone rocks, would have been, 

 which interlay the coals of the whole field ; and from whence, the internal 

 structure of the same would have been incomparably more visibly and use- 

 fully shown, than at present. 



f III the minuter details of the coal districts, Mr. Farcy used this other 



principle 



