444 



THE GEOLOGIST. 



to a veibical position, is not mapped by the government surveyors, so that tho 

 geological features of the district are not yet fully known. Altogether, there is 

 fine work for geologic study about the Great and Little Orme, and such may be, 

 in other eyes than mine, not the least advantage to be derived from a trip to 

 Llandudno. — George E. Roberts, Kidderminster." 



1)ISTUEBANCES IN THE TwELFTH AND THIRTEENTH CENTURIES. " NicholaS 



Trevet, in his annals, states that in 1155, the first year of Henry the Second, 

 ' Quintodecimo caL Martii, terrse motu horribili facto in Burgundia absorptum 

 est casteilum quoddam juxta Cluniacum, et locus castelli repletus est aqua incB- 

 timabilis profunditatis.' Again, in 1248, the thirty-second year of Henry the 

 Third, 'Temporibus Frederici, in Burgundia imperiali per terram solutam a 

 montibus circiter qu'mque niillia hominum suffocantur. Nam unus mons maxi- 

 mus, se dividens ab aliis moKtibus, per plura milliaria cujusdam vallis cadendo se 

 extendens, ad alios moutes accessit, omnes in valle villas terra et lapidibus 

 operiendo.' Is the site of the castle still covered by water of unknov/n depth, 

 and are any particulars known of the terrible landslip ? Local tradition will 

 doubtlesshave preserved some of the details. — John Jones, Gloucester." 



J\Iammalian Rejiiains. — "Dear Sir, — In pursuance of the request of Mr. 

 Prestwich with regard to the fauna of the quarternary epoch, I beg to state that 

 the Museum of the Isle of Wight, in Newport, contains teeth, scapula, and 

 humerus of Elephas primigenius. They were found in a thin bed of gravel, 

 beneath the brick-earth (five feet thick). The locality was a Vcilley between 

 chalk hills, one mile south of this town, in the line of the fault of the Medina. 

 A similar stratum four miles north-east of Newport yielded an elephant's tusk — 

 locality, valley of the Tertiary. Bones of the same animal, and others, are found 

 in the drift overlying the Wealden beds at Brook and Brixton. Details can be 

 had from, yours faithfully, Ernest P. Wilkins, F.G.S., Newport, Isle of Wight." 



The Stratigraphical Catalogue of Fossils. — " Sir, — Whilst admiring the 

 research and scholarship of Professor Morris' articles in your Journal, entitled 

 * British Fossils Stratigraphically Arranged,' I am surprised to find that in the 

 list of the literature on the Silurian Rocks there should be no mention of the 

 contributions of Hugh Miller. He has contributed to our science at least the 

 following : — « On the Ancient Grauwacke Rocks of Scotland ' (Old Red Sandstone, 

 8th edition, pages 297-324). ' On the Less-known Fossil Floras of Scotland,' 

 Part 1, (Testimony of the Rocks, page 423). These pages referring to the 

 Palaeozoic Rocks are invaluable to us in Scotland; and in justice to the research 

 and memory of one who has done so much for Geology, at least in our portion of 

 the island, it is but right they should be recorded in any list, so complete in every 

 way as that of Mr. Morris. I trust a long career of usefulness awaits your 

 Magazine. — Yours &c., A Subscriber." 



Manner of cutting Films of Selenite. — " Sir, — Would any of your readers 

 who are acquainted with polarizing matters, give directions for cutting films of 

 selenite of equal thickness to show a uniform colour throughout, suitable for 

 placing on the microscope-stage, or for constructing those stars and other devices 

 which are used with polarizing apparatus ? The pen-knife seems only to separate 

 unequal slips showing various colours and filled with a multitude of cracks. — 

 Yours &c., G. GuYON, Richmond, Surrey. 



Note on Central Heat. — "Sib, — The experiments of Arago, Cordier, Fox, 

 Ch-eenwell, and many other observers, have satisfactorily established the fact that 

 the internal temperature of the earth increases in proportion to the depth 

 descended, and that this increase may, most probably, be assumed as varying from 

 1 deg. Fahr. in 45 English feet, to 1 deg. in 60 English feet. Considering the 

 various conductive powers of the materials of wdiich the crust of the earth is 

 (Hmiposed, this is probably as near an average as can be arrived at. It would, 

 however, from our general notions of the laws governing the diffusion of caloric, 

 appear more natural that the heat should not increase directly as the depth, but 

 rather as the square of the distance from the earth's centre. It is on this point I 

 whsh to make a note. If we take E for the radius of the globe, and a; x, to 

 represent tho depth of two observations, we should have, assuming the law of th^ 



