316 Glass. — Earthquakes. — Extraordinary Visitation, 



with gneiss, primary sandstone, micaceous schist, and, if we do 

 not misapprehend tlie statements, clay slate, 



METHOD OF nENDERING GLASS LESS BRITTLE. 



Let the glass vessel be put into a vessel of cold water, and let 

 this water be heated boiling hot, and then allowed to cool slowly 

 of itself, without taking out the glass. Glasses treated in this 

 way may, while cold, be suddenly filled with boiling hot water 

 without any risk of their cracking. The gentleman who commu- 

 nicates the method, says that he has often cooled such glasses to 

 the temperature of 10°, and poured boiling water into them with- 

 out experiencing any inconvenience from the suddenness of the 

 change. If the glasses are to be exposed to a higher tempera- 

 ture than that of boiling water, boil them in oil. — An7iales de 

 Chim. et de Phys. ix. 



EARTHQUAKES. 



Three dreadful earthquakes took place at Copiapo on the 3d, 

 4th, and 1 1th of April. The whole city is said to have been de- 

 stroyed by these awful visitations. More ilian three thousand 

 persons were traversing the neighbouring plains, flying from the 

 desolation which had been produced. It appears, according to 

 all the accounts, that the inhabitants had time to save their lives, 

 but only their lives. Copiapo is a sea port of Chili, and stands 

 on the south side of a river of the same name, about 490 miles 

 N. by E. of Valparaiso. 



Another severe shock of an earthquake was felt in Trinidad 

 on the 12th of August at half past 2 A. M. A rushing noise as of 

 a violent wind was first heard, which was instantly succeeded by 

 an undulatory motion from east to west, very severe, and which 

 lasted four or five seconds. It was a clear moonlight night, and 

 nothing particular was discernible in the state of the atmosphere. 



On the 15th of August, a shock, accompanied with an explo- 

 sion as loud as that of a cannon, was felt at the village of St, 

 Andrews, in Lower Canada. 



EXTRAORDINARY VISITATION. 



A letter from Green Bay, Mich. Territory, United States, 

 dated July 19, 1819, gives the following very curious account of 

 the visitation of that country by clouds of insects, which will bear 

 a comparison with the swarms which heretofore darkened the air 

 of Egypt in their flight : 



" Within the last four pr five days the fly has appeared — a 

 non-descript perhaps in natural history — and covered the face of 

 the whole earth, obscuring the sun, moon, and stars. I write li- 

 terally, and without the least'exaggeration. The heavens are 



darkened 



