VOL. LVI.] PHILOSOPHICAL TRANSACTIONS. 277 



The rhinoceros of the year 1739, described in the Transactions, was three 

 years old; and the horn not three inches high; and hence by comparing that 

 with this, one may imagine this to be many years old, perhaps above twenty; 

 and that this animal lives to a great age. It is also plain that the horns are per- 

 petual as are those of oxen. 



VII. Extract of Tivo Letters, dated Dec. 7, and 12, \ 7^5, from the Rev. 

 William Borlase, of Ludgvan, Cornwall, F, R. S. to Emanuel Mendes da 

 Costa, Librarian, ^c. to the R. S. p. 35. 



As the existence of native tin is absolutely denied by all mineralists both an- 

 cient and modern ; and at the time Mr. B. wrote his Natural History of Corn- 

 wall, having no evidences to prove the contrary, he contented himself with sug- 

 gesting that its existence was far from being improbable, and in that manner he 

 left the dispute undecided. But a fortunate discovery, which had furnished 

 him with 3 specimens of this metal, native, or pure, would exclude all fur- 

 ther doubt. The account of it is as follows. In the month of May 1765 was 

 found near St. Austle, a large cake, or nodule, of tin ore, weighing about 61b, 

 irregular in shape, cracked or jagged at the edges, lying about 5 feet under the 

 surface, and in the middle of that stratum of tin ore, so remarkably spread in 

 the moor adjoining to the forementioned town. When the lump was broken, 

 it appeared to consist of two coats or incrustations, surrounding the whole, and 

 of a nucleus or central substance of a quartz, intermixed with the purest 

 malleable tin. 



Of the first specimen, the outer crust was about \ of an inch thick at a 

 medium, and of a brownish straw colour; the 2d or inner coat was blacker, 

 closer grained, with some faint appearances of whitish specks interspersed, and 

 about 4 of an inch thick; these two coats inclosed a third substance, consisting 

 of laminated crystals, rising side by side out of an edging, which shines like 

 melted tin, and lies as it were at their roots, coherent to the 2d coat. These 

 crystalline laminae are thin almost as the flakes or scales of talc, and being shot 

 in a great variety of directions, intersect each other, and leave a vast number of 

 cells, within which are plainly seen, and may be cut freely with a knife, many 

 specks and granules of pure native tin. 



The 2d specimen, which he sent to the Museum of the r. s. was of the same 

 structure, and part of the above-described lump, but much richer in quality. 

 Besides all the appearances of native tin taken notice of in the former specimen, 

 in this N° 2, was seen the malleable tin, in colour equal to the finest tin of the 

 fAimace, more liberally and distinctly dispersed. The metal is not only found in 

 granules, but in a foliaceous manner issuing out of the quartz, and formed like 

 a thick, jagged, or scalloped lace or edging, of which the specimen itself only 



