174 TENTH ANNUAL REPORT, ETC. 



passing through an atmosphere for ages, and none have yet encountered 

 the body of the earth. 



To sum up the theory of the lunar origin of meteorites,^ it may he 

 stated — That the moon is the only large body in space of ivhich ive have 

 any knoidedge, j^ossessing the requisite conditions demanded hy the 

 physical and chemical properties of meteorites ; and that they have been 

 throivn of from that body by volcanic action, (doubtless long since ex- 

 tinct,) or some other disruptive force, and, encountering no gaseous me- 

 dium, of resistance, readied such a distance as that the moon exercised 

 no longer a preponderating attraction — the detached fragment possessing 

 an orbital motion and an orbital velocity, ivhich it had in common^ with 

 all parts of the moon, but now more or less modified by the projectile 

 force and new condition of attraction in ivhich it was placed with refer- 

 ence to the earth, acquired an independent orbit more or less elliptical. 

 This orbit, necessarily subject to great disturbing influences, may sooner 

 or later cross our atmosphere andbe intercepted by the body of the globe. 



