VOL. I.] PHILOSOPHICAL TRANSACTIONS. 121 



folds, and near their head they have three feet on each side, which have but 

 two joints, resembling those of a louse. When they move, their body is com- 

 monly upwards, with their mouth against the stone. They have a large head, 

 somewhat flat and even, of the colour of a tortoise shell, with some small white, 

 hair. Their mouth is also large, where may be seen four kinds of jaw-bones, 

 lying crosswise, which they move continually, opening and shutting them like a 

 pair of compasses with four branches. The jaws, on both sides of the mouth, 

 are all black ; the nether-jaw has a point like the sting of a bee, but uniform. 

 They draw threads out of their mouth with their fore-feet, using that point to 

 range them, and to form their shells of them. They have ten eyes, very black 

 and rounds which appear to be larger than a pin's head. There are five of them 

 on each side of the head. 



Besides these worms, I have found that mortar is eaten by an immense num- 

 ber of small creatures, of the size of cheese mites. These have but two eyes, 

 and are blackish. They have four feet on each side pretty long. The point of 

 their muzzle is very sharp, like that of a spider. 



You may observe more of them in walls exposed to the south than in others. 

 The worms that eat the stone live longer than those that eat the mortar, which 

 scarcely live above eight days. I have observed all their parts with a good mi- 

 croscope, without which, and a great deal of attention, it is difficult to see them 

 well. 



I have seen other very old walls altogether eaten, as those of the Temple at 

 Paris, where I could find no worms, but the cavities were full of shells of vari- 

 ous kinds, diversely figured and turned ; all which I believe to be little animals 

 petrified. 



Some promiscuous Observations made i?i Somersetshire, and imparted 

 hy Dr Beale. N' 18, p. 323. 



This paper contains only notice of a quantity of oak trees found lying a little 

 under the surface of the earth near Bridgwater. Also of some water that cattle 

 would not drink in the driest seasons. And of quantities of dead eels found in 

 holes under the ice. 



To find the Year of the Julian Period, hy a new and very easy Method. 

 By M. J. De Billy.'' iSf" 18, p. 324. 



Multiply the solar cycle by 4845, and the lunar by 4200, and that of the in- 



* Father James de Billy was a learned French Jesuit, in the 17th century, bom in Corapeigne 

 1602, and died at Dijon 16/9* at 77 years of age. He wrote several mathematical works ; as^ 

 VOL. I. Q 



