VOL. XLVI.] PHILOSOPHICAL TRANSACTIONS. 675 



Years Error of Years Error of Years Error of Years Error of Years Error of 

 A.c. Tables. a.d. Tables. a.d. Tables. a.d. Tables. a.d. Tables. 



700 — 56' 6" 200 — 28' 30" 300 — 9' 20" 800 + 1' 30" 1300 + 4' 0" 



600 — 49 50 100 — 24 400—6 30 900 + 2 40 1400 + 3 30 



500 — 44 a.d.O — 19 50 500 — 4 1000 + 3 30 1500 + 2 40 



400 — 38 30 100 — l6 600 — 1 50 1100 + 4 l600 + 1 30 



300 — 33 20 200 — 12 30 700 1200 + 4 10 1700 



Some Histories of Morbid Structure observed in Dead Bodies.* By Albert Haller, 

 Archiater, Professor of Physic at Gottingen, and F.R.S. N" 492, p. 172. 



On the Lacrymte Batavic^e, or Glass Drops, the Tempering of Steel, and Effer- 

 vescence, accounted for by the same Principle. By Claud. Nic. le Cat, AI.D., 

 F.R.S. N''492, p. 175. 



The glass-tear, or drop, commonly called lacryma Batavica, or lacryma Bo- 

 russica, because it was first made in these countries, is much celebrated among 

 natural philosophers, on account of the singular phenomena which it exhibits, 

 and which have for a long time exercised their sagacity. The make of this drop 

 is as simple as its explanation is difficult. It is the work of the meanest work- 

 man in a glass-house. On the top of an iron rod they take up a small quantity 

 of the matter of glass in fusion: they let it drop into a pail of water : the drop 

 makes that part of the water which it touches to boil with a hissing noise, as a 

 red-hot iron does, which it resembles in that instant; and when it does not 

 break in this operation, as it most frequently does, it forms the little pyramidal 

 mass, which is known by the name of a glass drop. 



This drop is of such hardness and resistance, that it bears smart blows of a 

 hammer, without breaking. Yet if you grind the surface of this drop which re- 

 sisted the hammer, or if you only break the tip of the small end or tail, the whole 

 shatters into powder. This shattering of the drops is attended with a loud re- 

 port : and the dust or powder to which it is reduced, darts out, and scatters all 

 around. If the drop be ground with powder of emery, imbibed with oil, it often 

 escapes breaking. If this experiment be made in the air-pump, the drop bursts 

 with greater impetuosity, so as sometimes to break the receiver ; and its dust is 

 finer than when done in the open air ; and if it be made in the dark, the drop in 

 bursting produces a small light. If this drop be annealed in the fire, it loses all 

 these singularities; and being reduced to the state of common glass, it easily 

 breaks under the hammer, , and does not burst on breaking the small end. Th? 

 drops that are made by letting them cool in the air, produce no other effects than 

 those which have been annealed. 



* By some oversight, this paper is a republication of that inserted in the Phil. Trans. N' 483, vol. 

 xliv. and at p. 348, vol. ix. of these Abridgements. 



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