PROGRESS OF METEORIC ASTRONOMY IN AMERICA. 291 
From data obtained from the observations of the Novem¬ 
ber meteors of 1867 at the U. S. Naval Observatory and at 
Richmond, Va., Prof. S. Newcomb l , U. S. N., computed the 
altitude of nine meteors, finding the mean altitude at appari¬ 
tion to be 102 miles, and at disappearance 47 miles. From 
data obtained from observations on the same occasion, Prof. 
W. Harkness 2 3 , U. S. N., discussed a method of determining 
the mass of such meteors as are consumed before reaching 
the earth. 
Assuming that the light produced is always proportional 
to the amount of material consumed, he arrived at the con¬ 
clusion that “ the mass of the ordinary shooting-stars does 
not differ greatly from one grain.” 
In 1869 a paper by Prof Daniel Kirkwood? on “ Comets 
and Meteors ” was devoted to exhibiting the probable coin¬ 
cidences* between the orbits of comets and periodical meteors. 
In 1871 Mr. Jacob Ennis 4 published a paper entitled “The 
meteors and their long-enduring trails.” 
The scope and method of this paper are briefly sketched 
by the author, and are best presented in his own words, as 
follows: 
“ Firstly, I will bring forward many facts to prove that 
some meteors undergo a process of burning or oxidation 
while passing through the air, and that the trails are the 
smoke and ashes of such burning. 
“ Secondly, I will give facts and reasoning which show that 
some meteors are composed of various simple chemical ele¬ 
ments unoxidized, and which are therefore capable of burn¬ 
ing in the air. 
“ Thirdly, I will show the order and process of creation by 
which such meteors were originally formed and left in an 
unoxidized condition. ” 
These points are discussed at length, and numerous theories 
and observations are cited as proof. 
1 A. J. S., XLV 2 , 233. 2 A. j. S ., XLV 2 , 237. 
3 Proc. Am. Phil. Soc., XI, 215. 4 Proc. A. A. A. S. 1871, 122. 
36—Bull. Phil. Soc., Wash., Vol. 11. 
