8^8 PHILOSOPHICAL TRANSACTIONS. [aNNO I76g, 



the account of it, published in the Transactions of the year following, was not 

 such as I wish, yet I am steadily intent on paying my duty to the Society, and 

 obviating (as far as lies in my power) all doubts relating to natural knowledge. 



Last post I received a letter from Mr. Rosewarne, of this county, with an ac- 

 count of his having met with another specimen of native tin ; and I send it 

 inclosed, for your inspection, to be returned at your leisure. 



To the Rev. Doctor fV. Borlase. 



Truro, Jan. 27, 1769. 

 I have the pleasure to acquaint you, says Mr. Rosewarne, that I have at last 

 met with a specimen of native tin, which is so evidently so at first sight as not 

 to admit of the least doubt or objection. The description of it is this : some 

 streamers in the parish of Luxilion brought in a parcel of tin ore to a blowing- 

 house I am concerned in at Sthurtle; among the parcel was a great number of 

 tin diamonds of a most beautiful nature, of the rozin kind ; one was eminently 

 superior to the rest, being almost transparent, and seemed to have something in 

 the centre which, through the stone, looked like gold. This induced me to 

 break the stone; which was no sooner done than I found it to be native tin, in 

 the very centre of the diamond. The specimen is so small, that I am at a loss 

 which way to send it for your inspection, for fear it should be lost. I • shall set 

 out for London on Monday next, and intend carrying this curiosity with me. 

 I'll not leave it behind me ; but when I come back you shall see it, and through 

 you deposit it with the r. s. for the satisfaction of the curious." 



f^IIL On the Origin of a Natural Paper, found near the City of Cortona in 

 Tuscany. By John Strange, Esq., F. R. S. p. 50. 



In August 1763, some low grounds, in a farm about four miles south-west of 

 Cortona, which had been flooded, were found covered with a substance very 

 much like a finer sort of common brown paper. A circumstantial account of 

 the fact was communicated to the public the September following, in a letter 

 from Mr. Coltellini to Dr. Lami, professor of theology at Florence. This 

 account surprised, and excited the curiosity of the naturalists in Italy ; and 

 various were the conjectures offered on the occasion. The prevailing opi- 

 nion however attributed the formation of this paper to a casual aggregate of the 

 fibres of difierent kinds of filamentous plants, collected together by the waters, 

 and left on the surface of the ground at their retreat. This supposition seemed 

 plausible enough, since such a mechanism could be produced only by filamentous 

 plants; most of which are commonly the spontaneous productions of such low, 

 marshy ground. But on considering that, in the paper manufactures of difl^erent 

 countries, various degrees and methods of maceration are requisite, according to 

 the respective qualities of the fibres of difi^erent plants ; it appeared very difficult 



