224 PHILOSOPHICAL TRANSACTIONS. [aNNOISQ?. 



the evaporation of the moisture. After two months, viz. the beginning of 

 August, the eggs began to hatch, and two or three young snails daily appeared. 



I looked (says M. L.) several times on a snail, as it sat inwards, against the 

 glass, and to my great satisfaction, I could see through the shell and part of the 

 snail, which seemed not larger than an oidinary grain of sand, having the figure 

 of a common egg. The body of the snail was partly retracted and extended again, 

 which motion happened in as little time as we may easily pronounce a word of 

 4 syllables. 



I have often wondered in the spring, to see those little snails so early on the 

 tops and branches of the vine, because I could not imagine that the snails 

 should have brought forth their young so early in the year. But now we see, 

 that they come forth out of eggs ; and thus we can easily comprehend that 

 these eggs lay in the earth all the winter, and by the first warm weather 

 are hatched. 



Having afterwards procured a very large snail, I put it up in a glass tube, 

 being so large that the snail could turn itself in it, and about 10 inches long;. 

 The snail had not been there half an hour, before it had brought forth on the 

 , glass 7 eggs, and about 1 hours after, 7 eggs more ; and when I looked on it 

 again, I found that the snail by creeping up and down had broken all the eggs 

 in the glass; so that there could be nothing discerned, except the membrane 

 of the eggs. This great snail died on the 2d day, probably for want of food, 

 without producing any more eggs. The young snails, which were come out 

 of the eggs, did not live above 2 or 3 days ; after which, I took them out of 

 the glass, and observed, that the membrane out of which the snails had come, 

 was very white ; and the rest of the eggs, which were fruitless, and out of 

 which no snail had come, had a dark watery colour. 



END OF VOLUME NINETEENTH OF THE ORIGINAL- 



^ccount of some Experiments about the Height of the Mercury in the Barometer, 

 at the Top and Bottom of the Monument: and about portable Barometers. 

 By Mr. JVilliam Derham*, Rector of Upminsler. N° 236, p. 2. Fol. XX. 



In Sept. 1696, I made observations on the monument, with 2 of Mr. Quare's 



* Dr. Wm. Berham, an eminent philosopher and divine, as well as a most useful member of the 

 Royal Society, was born at Stowton, near Worcester, Nov. 26, l657. He became a student at 

 Oxford, where he was soon distinguished for his learning in the languages, and his genius in philoso- 

 phical inquiries. Froni the vicarage of Wargravc in Berkshire^ which he held 7 years^ he wa» 



