THE SMITHSONIAN INSTITUTION. 169 



be known by tbeir fragments. With tbis view of the matter, our 

 specimens of meteorites are but multiplied samples of tlie same body, 

 and that body, with the light we now have, appears to have been the 

 moon. 



This theory is not usually opposed on the ground that the moon is 

 not able to supply such bodies as the meteoric iron and stone ; it is 

 more commonly objected to from the difficulty that there appears to 

 be in the way of this body's projecting masses of matter bej^ond the 

 central point of attraction between the eartli and moon. Suffice it to 

 saj^, that Laplace, with all his mathematical acumen, saw no difficulty 

 in the way of this taking place, althougli we know that he gave 

 special attention to it at three different times during a period of 

 thirty years, and died without discovering any physical difficulty in 

 the way. Also, for a period of forty years, Olbers was of the same 

 opinion, and changed his views, as already stated, for reasons [of a 

 different character. And to these two we add Hutton, Biot, Poisson, 

 and otliers^ whose names have been already mentioned. 



Laplace's view of the matter was connected with present volcanic 

 action in the moon, but there is every reason to believe that all such 

 action has long since ceased in the moon. This, however, does not 

 invalidate this theory in the least, for the force of projection and 

 modified attraction to which the detached masses were subjected, only 

 gave them new and independent orbits around the earth, that may 

 endure for a great length of time before coming in contact with the 

 earth. 



The various astronomers cited concur in the opinion, that a body 

 projected from the moon with a velocity of about eight thousand feet 

 per second, would go beyond the mutual point of attraction between 

 the earth and moon, and already having an orbital velocity, may be- 

 come a satellite of the earth with a modified orbit. 



The important question, then, for consideration, is the force requisite 

 to produce this velocity. The force exercised in terrestrial volcanoes 

 varies. According to Dr. Peters, who made observations on ^Etna, 

 the velocity of some of the stones was 1,250 feet a second, and obser- 

 vations made on the peak of Teneriffe gave 3,000 feet a second. Assu- 

 ming, however, the former velocity to be the maximum of terrestrial 

 volcanic effects, the velocity with which the bodies started (stones 

 with specific gravity of about 3.00) must have exceeded 2,000 feet 

 a second to permit of an absorbed velocity of 1,250 feet through the 

 denser portions of our atmosphere. 



When we regard the enormous craters of elevation on the moon's 

 surface, the great elevation of these above the general surface^ and 

 the consequent internal force required to elevate the melted lava that 

 must have at one time poured from their sides, it is not irrational to 

 assume that bodies were projected from lunar volcanoes at a velocity 

 exceeding seven or eight thousand feet per second. I know that Prof. 

 Dana, in a learned paper on the subject of lunar volcanoes, (Am. J. 

 Sci., [2], ii, 375,) argues that the great breadth of the craters is no 

 evidence of great projectile force, the pits being regarded as boiling 

 craters, where force for lofty projection could not accumulate. Al- 

 though his hypothesis is ingeniously sustained, still, until stronger 



