•200 PHILOSOPHICAL TKANSACTIONS. [aNNO 1746. 



adjacent. It probably contains mineral and metallic particles ; being a pon- 

 derous, hard, grey, stone, used for the most part in the basements and coins of 

 buildings. 



Hence it should seem not impossible for stone to be cast or run into the shape 

 of columns,* vases, statues, or relievos ; which experiment may perhaps, some 

 time or other, be attempted by the curious ; who, following where nature has 

 shown the way, may (possibly by the aid of certain salts and minerals) arrive at a 

 method for melting and running stone, both to their own profit, and that of 

 the public. 



Observations on a sort of Libella-\- or Ephemeron. By Mr. Peter Collinson, 



F.R.S. N°48l, p. 329. 



Walking by the river's side at Winchester, Mr. C. was told, that now was the 

 time of year that the May flies, a species of libella, came up out of the waters, 

 and were seen for a few days, and then disappeared. This excited his curiosity, 

 having never seen this insect. 



May 26, 1744, he was first shown it by the name of May fly, on account of its 

 annual appearance in that month. It lies all the year, except a few days, in the 

 bottom or sides of the river, near the likeness of the nymph of the small com- 

 mon libellas ; but when it is mature, it rises up to the surface of the water, and 

 splits open its case ; then, with great agility, up springs the new animal, with a 

 slender body, with 4 blackish-veined transparent shining wings, with 4 black 

 spots in the upper wings ; the under wings much smaller than the upper ones ; 

 with 3 long hairs in its tail. See pi. 7, fig. 2, 3, 4; where fig. 2 represents the 

 back of this insect; and fig. 3 and 4 side-views of the same. 



The husk or exuviae that it leaves behind floats innumerable on the water. It 

 seemed to him a species of ephemeron ; and he imagined it was the same insect 

 described by Goedart and Swammerdam ; but a few days convinced him other- 

 wise, for he soon found these had a longer duration than theirs. 



The next business, after this animal is disengaged from the water, is flying 

 about to find a proper place to fix on, as trees, bushes, &c. to wait for its ap- 

 proaching change, which is effected in 2 or 3 days. The first hint he received 

 of this wonderful operation, was seeing their exuviae hanging on a hedge. He 



• To confirm what the bishop says, I remember when I was in the college in France, that I went 

 to see a relation of mine, a frier, at Fontevrand, where he showed me in their church two pillars of 

 stone, about 60 feet high, all of one solid piece, which he said had been run. J. S. — Orig. 



+ I take this to be the musca tripilis mentioned in Moufet, Insect. Theat. p. 64, and may properly 

 be called musca, libellae affinis, cauda tripili. C. M. — Orig. 



This insect is the ephemera vulgata, Linn, or commmon May-fly. When Mr. Collinson speaks 

 of having never seen it, he must surely mean that he had never seen it in its early or nascent state. 



