330 J. Lawrence Smith on Meieorites. 
velocities.* Not even their effect on striking the earth, will furnish 
any data whereby to calculate their velocities before entering the 
atmosphere, for this medium must offer such enormous resistance 
to bodies penetrating at great velocities, that these velocities must 
be reduced to but a fraction of what they originally were, and it 
is a question whether a body entering our atmosphere at ten miles 
a second would penetrate the soil to a much: greater depth than 
one entering it at five miles a second, for the increased velocity 
of the former would cause an incre eased resistance in the atmo- 
sphere and therefore have received proportionally a greater check 
before striking the eart 
Another fact tending to prove a dissimilarity between shooting 
stars and meteoric stones, is that the velocity of no one of the 
shooting stars has been observed to be so low as to allow of their 
being considered satellites to the earth; their average velocity is 
164 miles a second and it requires a reduction to less than six 
miles a second for them to alt a a path around the earth. Now. 
assume what we may as to the original orbit of the. meteoric 
stones, and as to their ale velocity—let their orbit be around 
the sun and their velocity 16 miles a second—there is one thing 
we know, namely that these bodies do enter our atmosphere, an 
it is but right to assume, often pass through the atmosphere with- 
out falling to the earth, sometimes passing through the very Up- 
permost portion of that medium, at other times lower. Wha : 
becomes of their original assumed velocity after this passage? 
Ss it can be so — as to be drawn to the earth’s surface, and 
shes stopped altogether in its passage, their velocities may be 
changed to any velocity from 16 miles a second to zero, accord- 
ing to the amount of resistance it meets with ; and what is equally 
true in this connection, is, that when the velocity falls below six 
miles a second (or thereabouts) they can no longer escape from 
the attraction of the earth and resume their solar orbit, but must 
revolve as a satellite around the earth until ultimately brought 
to its surface by repeated disturbances. 
The deduction from the above fact, is as follows: that as the 
most correct observations have never given a velocity of less than 
* Under this head I will merely note what is considered one of ve ioe established, 
ly th 
cases of the determination of velocity of a meteoric stone—name of the Weston 
esti ceed yi miles @ sec- 
ed hie the duration 
the mete- 
we 
