594 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



the 14th of November last. To those in London and its vicinity, 

 the meteoric shower was at its maximum about* one o'clock a. m. 

 Meteors are constantly failing into our atmosphere, where, from 

 the intense heat generated by their rapid passage through a resist- 

 ing medium, they are dissipated before reaching the crust of the 

 earth. They are supposed to originate in a collection of isolated 

 bodies, forming a ring or zone, which revolves around the sun 

 either a little faster or slower than the earth. The difference in 

 the time of their revolutions, or the 3'ear of this zone and of the 

 earth, is about eleven days. A given point in the zone would be 

 opposite to the earth once in about thirty-three years ; conse- 

 quently, it was inferred a great shower, similar- to that of 1833, 

 would be visible in 1866. On the 10th of August in every year, 

 there is an unusual display of meteors, hence some astronomers 

 conclude that the zone intersects the earth's orbit at a point which 

 the earth passes on that da}'. 



Meteorites, often found imbedded in the soil, are generally sup- 

 posed to have the same origin as meteors, but, being of greater 

 density, they are not volatilized in their descent. At least 18 of 

 the chemical elements known to us are found in meteorites, which 

 are classified under the names, "meteoric iron" and "meteoric 

 stones." The former contain an average of about 90 per cent, of 

 iron, from five to eight per cent, of nickel, and small quantities of 

 other magnetic metals, with traces of several metalloids, generally 

 excluding oxygen. The latter class are composed principally of 

 silicates. Prof. Sheppard, of Amherst College, has found in mete- 

 orites several minerals not heretofore met with. Meteorites — the 

 earth's only foreign visitors — are objects of great * interest to 

 scientists, who hope, by analysis, to learn the secret of their 

 birth. Some persons have conjectured that they have traveled 

 from our nearest recognized neighbor, the moon. "A body would 

 have to leave her surface with a velocity of about 7,770 feet per 

 second, or 88 miles per minute, to pass beyond her gravitating 

 influence, and within the superior attracting power of the earth. 



Caoutchouc and Gutta Pekcha Cement. 

 India rubber, at about 400 dcg. F., is converted into a gliitenous 

 mass. By the addition of fresh slacked lime to twice its weight 

 of gum-elastic, or rubber in this state, a non-drying cement of great 

 tenacity is formed, and is used in fastening together plates of glass 

 so as to exclude the air, but which may easily be separated. A 



