444 
THB GEOLOGIST. 
to a vertical position, is not mapped by tlie government surveyors, so that the 
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. — Geoege E. Roberts, Kidderminster." 
DlSIUBEANCES IN THE TWELFTH AND ThIKTEENTH CENTURIES. — " NicholaS 
Trcvet, in his annals, states that in 1155, the first year of Henry the Second, 
' Quintodecimo cal. Martii, terra; motu horribili facto in Burgundia absorptum 
est castcllum quoddam juxta Ciuniacum, ct locus castclli repletus est aqua incs- 
timabilis profunditatis.' Again, in 1248, the thirty-second year of Henry the 
Third, 'Temporibus Frederici, in Burgundia imperiali per terram solutam a 
montibus circiter quinque millia hominum sulfocautur. Nam unus mons maxi- 
mus, se dividens ab aliis montibus, per plura milliaria cujusdam vallis cadendo se 
estendeijs, ad alios monies accessit, omnes in valle villas terra et lapidibus 
opericndo.' Is the site of the castle still covered by water of unknown depth, 
and are any particulars known of the terrible landslip ? Local tradition will 
doubtlesshave preserved some of the details. — John Jones, Gloucester." 
Mammalian REjrAiNS. — " 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 primigcnius. They were found in a thin bed of gravel, 
beneath the brick-earth (five feet thick). The locality was a valley between 
chalk hills, one mile south of this town, in the line of the fault of the Medina. 
A simiiar stratum four miles north-east of Newport yielded an elephant's tusk — 
locality, valley of the Tertiary. Bones of the same animal, and others, arc found 
in the driit overlying the Wealden beds at Brook and Brixton. Details can be 
had from, yours faithfully, Ernest P. AVilkins, F.G.S., Newport, Isle of Wight." 
The Stiiatigeapuical 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 Subscehjer. ' 
Manker of cutting Films of Selenite. — " Sir, — Would any of your readers 
■who arc 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 micioscope-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. GuTON, Richmond, Sui-rey. 
Note on Central Heat. — " Sir, — The experiments of Arago, Cordier, Fox, 
GreenweU, and many other observers, have satisfactorily established the fact tliat 
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 which the crust of the earth is 
composed, this is probably as near an average as can be arrived at. It would, 
however, from our general notions of the laws governing the difi'usion of caloric, 
appear more natural that the heat should not increase directly as the depth, but 
rather as the square of the distance fi-oni the earth's centre. It is on this point I 
wish to make a note. If we take R for the radius of the globe, and z z, to 
represent the depth of two observations, we should have, assuming the law of the 
