16q, philosophical transaction's. [anno 1745, 



received from Dr. Laurentius Bruni of Turin, ' taking notice of the same ; and 

 relating their remarkable property of resisting very hard strokes that were given 

 them from without, notwithstanding they at the same time shivered to pieces on 

 the shocks they received by the fall of very light and minute bodies dropped into 

 their cavities. And Mr. Ellicot, having very soon after caused some unnealed 

 glasses to be made here, repeated with them some of the same experiments, 

 which he found to answer agreeably to what Dr. Bruni had mentioned. 



But it will further appear to be remarkable in the present paper, that, accord- 

 ing to the experiments made abroad on those glasses, it is not the weight alone 

 of the bodies severally dropped into them, which occasions their rupture; for 

 some certain bodies break them with abundantly more ease than others of the 

 same or even much greater weights; insomuch that such phials as are shivered 

 to pieces by the fall of very small particles of flint and some other substances, 

 are nevertheless capable of resisting the much greater shock they receive, in like 

 manner, from a leaden bullet, though some hundreds of times heavier than the 

 flint. 



The author of the paper is Mons. Allamand, a gentleman of distinction, 

 merit, and learning, in Holland, a person of great curiosity, and particularly 

 well versed in all the parts of natural and experimental knowledge. This gentle- 

 man comijiunicated his observations to the Hon. William Bentinck, Esq. of the 

 Hague, a worthy member of the Royal Society, and who was pleased immediately 

 not only to transmit them over to the president, but also to oblige him at the 

 same time, with a number of glass phials, of the very same sort as those on 

 which Mons. Allamand's experiments had been made, that he might thereby be 

 enabled both to report to the society the facts he should take notice of, and to 

 repeat some of the experiments themselves in their presence. 



Mons. Allamand's paper is in French, but the substance of it in English is as 

 follows : 



These glasses differ from ordinary phials only in this, that they have not been 

 set to cool gradually in what is called the nealing furnace, but have been imme- 

 diately exposed to the open air as soon as formed. They may be made of any 

 shape; and all that needs to be observed in the making of them is, to take care 

 tiiat their bottoms may be thicker than their sides, and indeed the thicker the 

 bottom is, the easier the glasses break. Mr. A. had one in particular, whose 

 bottom was above 3 fingers breadth in thickness, and which flew with as much 

 ease at least as the thinnest glass. He had some others equally thick all over; 

 these have flown also, but with more difficulty than the former. 



These glasses are capable of resisting very hard blows coming from without: 

 he has given to some, with a mallet, strokes sufficient to drive a nail into wood 

 tolerably hard, and they have held good without breaking. They also resist the 



