132 lftature'0 



out of 100 shooting stars twenty-two of them 

 had an elevation of over twenty-four and less 

 than forty miles; thirty-five, between forty 

 and fifty miles; and thirteen between seventy 

 and eighty miles. It was determined by Pro- 

 fessor Herschel that out of sixty observations 

 of shooting stars the average height of their 

 first appearance was seventy-eight miles and 

 their disappearance was at a point fifty-three 

 miles above the earth. 



It is a matter of history, however, that 

 sometimes these meteoric stones descend to 

 the surface of the earth before they are en- 

 tirely disintegrated. A fine specimen of this 

 kind is to be seen in the Smithsonian Institu- 

 tion. There are over forty specimens of these 

 aerolites (air-stones) in the British Museum, 

 labeled with the times and places of their 

 fall. Instances of falling to the earth are so 

 rare that there is little to fear from these wan- 

 dering missiles of the air. We do not remem- 

 ber a case where life or property has suffered 

 from the fall of a meteor. 



This brings us to the consideration of the 

 part which the great air envelope surrounding 

 the earth plays as a protection against many 

 outside influences. For instance, if it were 

 not for the air, millions of these meteoric 

 stones would be showered upon our earth every 

 year and at certain times every day, which 

 would render the earth untenable for human 



