294 MEMOIR ON METEORITES. 



prepared to note the data requisite for calculating their veloci- 

 ties ; besides, I am prepared to prove that the two or three 

 cases of supposed determination of velocities of meteoric stones 

 can not be considered even gross approximation to the truth ; 

 in fact, the difficulties in the way are so great that we probably 

 never shall arrive at a knowledge of their velocities.* Not 

 even their effect on striking the earth will furnish any data 

 whereby to calculate their velocities before entering the atmos- 

 phere, 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 increased resistance in 

 the atmosphere, and therefore have received proportionally a 

 greater check before striking the earth. 



Another fact tending to prove a dissimilarity between shoot- 

 ing-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 sixteen and a half miles a second, and it requires a reduction 

 to less than six miles a second for them to assume a path around 

 the earth. Now assume what we may as to the original orbit 

 of the meteoric stones, and as to their original velocity — let 



* Under this head I will merely note what is considered one of the hest 

 established cases of the determination of velocity of a meteoric stone; namely, 

 that of the Weston meteorite, the velocity of which Dr. Bowditch estimated 

 to " exceed three miles a second." Mr. Herrick considers the velocity very 

 much greater, and writes among other things what follows: "The length 

 of its path, from the observations made at Eutland, Vt., and at Weston, 

 was at least one hundred and seven miles. This space being divided by the 

 duration of the flight as estimated by two observers — viz., thirty seconds — 

 we have for the meteor's relative velocity about three and a half miles a 

 second. The observations made at Wenham, Mass., are probably less exact in 

 this respect, and need not be mentioned here. An experienced observer, how- 

 ever intelligent, will give the time ten or even twenty-fold too large. One not 

 unversed in science who saw the meteor is confident it could not have been 

 in sight as long as ten seconds." The above is given as a specimen of the 

 uncertain data we are to proceed upon in estimating the velocity of meteoric 

 stones. 



