40^ FHILOSOPHICAL TBANSACTIONS. [aNNO 1733. 



able substance, which, on the specimen sent over by the professor, he has intitled 

 " a sort, perhaps, of alcyonium molle," is a species of that genus of plants, 

 which the more modem botanists call byssus. And it is of that species, or a very 

 slight variety from it, which is called by Dillenius, in his Historia Muscorum, 

 byssus tenerrima viridis velutum referens. It is also mentioned and figured by 

 Micheli in his Nova Plantarum Genera, under the title of byssus terrestris viridis 

 herbacea et mollissima, filamentis ramosis et non ramosis. This genus of plants, 

 in the order of nature, comes between the mosses and fungi. The specimen 

 now sent, being white on one side, arises from its either being washed or 

 bleached by the sun; for when wet, according to Mr. Bose, it was green; and 

 this colour is mentioned both by Dillenius and Micheli in their several denomi- 

 nations. This vegetable is found in England, as well as in many parts of 

 Europe, in moist meadows, covering the ground like a carpet, and sometimes to 

 a great extent. 



We must be careful, however, how we connect the substance in question, and 

 others of the same genus with the jSuVo-of of the ancient Greek writers, or the 

 byssus of the Latin. What that substance was, has been matter of great con- 

 troversy. This is certain, that garments made of it were the apparel of the rich. 

 And in the New Testament, St. Luke, in the parable of the rich man and 

 Lazarus, says of the former, as a mark of his opulence, IviSiSda-niTo Trof<pv^a,v xal 

 jSuVirov ; this is translated in our English version, " he was clothed in purple and 

 fine linen." It is more probable, that the byssus of the ancients was a very fine 

 sort of cotton ; but whoever wishes to examine what has been said on this sub- 

 ject, may consult Pliny* and Wormius;-j- but, above all, Bodaeus a Stapel,;}; 

 in his Commentary on Theophrastus; who has on this occasion, as well as on 

 many others, given us an ample testimony of his vast erudition. 



LV^. Account of a Memoir read at the Royal Academy of Sciences at Paris, by 

 M. de Barros, a Portuguese Gentleman, concerning certain Phenomena ob- 

 served by him at Paris, in the last Transit of Mercury over the Sun. By J. 

 Short, A. M., F. R. S. p. 36l. 



The author says, he used an excellent Gregorian reflector 4 feet in length, 

 taking in the eye-piece, and as much of the great tube, as exceeds the focal 

 lengths of the two eye-glasses; probably it should be the two speculums: that 

 the focus of the great speculum is 33 Paris inches; that of the small one 4 

 inches ; the focus of the eye-glass next the eye 1 8 lines ; the focus of the glass 

 farthest from the eye 5 inches; and, lastly, that the combined power of these 2 

 glasses is nearly equal to that of a single eye-glass of 3 inches. The telescope 



• Plinii lib. xix, c 1 . + Mus. p. 139. % P> 425, et seq. 



