VOL. XXII.] PHILOSOPHICAL TRANSACTIONS. 511 



after I had conveyed into it a bit of cheese, that the worm might come to its 

 full growth and change. At the end of 14 days I observed it was changed into 

 a tonneken,* though it did not seem to be arrived at its full growth, which 

 made me believe it would never be a fly, but I was mistaken, for soon after I 

 spied the fly leaping about the glass, and the empty tonneken by it. I send 

 you the said dead fly, and the tonneken inclosed in N° 1. In N"" 2 are several 

 empty tonnekens, and the flies that came out of them, all which proceeded 

 from mites that one of our cheesemongers helped me to; and by comparing 

 yours and mine together, you will easily observe that they are alike in all their 

 parts. 



On the Catacombs at Rome and Naples. Bij John Monro, M. D. N° l6b, p. 643. 



The catacombs are a narrow gallery, dug a vast way under ground, with an 

 infinite number of others going off from it on all sides, and also a vast number 

 of little rooms going off from the principal, and the secundaries too. Those of 

 San Sebastiano, of San Lorenzo, of Sant Agnese, and the others in the fields 

 a little off from Sant Agnese, are commonly shown to strangers. They take their 

 names from the churches in their neighbourhood, and seem to divide the cir- 

 cumference of the city without the walls between them, extending their galleries 

 every where under it, and a vast way from it, so that all the ground under it, 

 and for many miles about it, is said to be hollow. Now there are two sorts of 

 authors that run into extravagance on this subject ; the one will have them made 

 by the Primitive Christians, adding, that in the times of persecution, they lived, 

 held their assemblies, and laid up the bodies of their martyrs and confessors in 

 them. This is the account that prevails at Rome, and in consequence of it men 

 are kept constantly at work in tiiem. As soon as these labourers discover a re- 

 pository, with any of the marks of a saint about it, intimation is given to the 

 cardinal treasurer, who immediately sends men of probity and reputation to the 

 place ; where they find a palm painted or engraven, or the cypher Xp, which is 

 commonly read pro Christo, or a small round projection in the side of the gal- 

 lery, a little below the repository ; what is found within it is carried to the 

 palace. Many of these projections we have seen open, with pieces of phials in 

 them ; the glass indeed was tinctured, and it is pretended, that in these phials 

 was preserved the blood of the martyrs, which was thus laid up near their bodies 

 towards the head, to distinguish them from those of others, wiio were not 

 called to the honour of laying down their lives for the faith of the gospel. 

 After the labourers have surveyed a gallery, they close up the entry that leads 



* Chrysalis. 



