Extract of a Letter from Dr. Josephus Laurentius Bruni, of Turin, F. R. S. to Mr. Henry Baker, F.R.S. concerning the Bologna Bottles

IX. Extract of a Letter from Dr. Josephus Laurentius Bruni, of Turin, F.R.S. to Mr. Henry Baker, F.R.S. concerning the Bologna Bottles. Dated at Turin, Nov. 1744. Dear Friend, THE Sced of the Gramen tremulum*, which you favoured me with, has amazed all here who have seen it. The curious People in this Country talk much of a Phænomenon, which is called of the Bologna Bottle, because it was first discover'd at Bologna. If you let these Bottles fall perpendicularly from some Height upon a Brick-Floor, they will not be broken; but if you drop into them some little hard Bodies, they will burst in Pieces. I will give you an Account of what I try'd myself about them. I took one of these glass Bottles, whose Form resembles a Florence Flask, and whose Capacity is about three Quarters of a Pint, and let it fall down from the Height of five Feet and half upon a Floor of Brick, and it was not broken: I then let fall down into it, from the Mouth to the Bottom internally, a Piece of Flint-Stone, weighing 11 Grains; and immediately the Bottle burst into many Pieces. I took one of those Pieces, weighing a Dram, and let it fall in the same manner into another Bottle, which I moved circularly for a Minute; and then putting * See these Transactions, No. 457. putting it upon a Table, in about a Quarter of an Hour it broke in Pieces. Into a third Bottle I dropped a Piece of Whetstone, weighing 40 Grains; and in some few Minutes the Bottle was broken. I filled another Bottle half-full of Water, and let fall into it a small Piece of Flint stone; and after four Hours it burst. I let fall into three other Bottles a Piece of Wood weighing 50 Grains, a Piece of Brass weighing 300 Grains, and a Ball of Lead weighing 140 Grains; and neither of them was broken. These Bottles are thicker at the Bottom than the Neck. The Glass-Maker blows them, and lets them cool, without putting them again into the Oven. And, from the Experiments, I take notice, that what is capable of breaking them ought to have some Roughness: And I am told that a Grain of River-Sand will break them. The first Opportunity I shall send you two or more of these Bottles; and am, &c. X. A Letter from Mr. Tho. Wright to James Theobald, Esq; F. R. S. concerning Two ancient Camps in Hampshire. Read Feb. 7. LAST Summer, during my Stay in the West of England, common Report, and my own natural Curiosity, led me to a Place in Hampshire called Buckland Castle, or, more vulgarly, the Rings; where I found two neighbouring Camps