PROGRESS OF METEORIC ASTRONOMY IN AMERICA. 287 
are grand reservoirs of latent heat most admirably adapted 
to the protection of the earth from collision with bodies ap¬ 
proaching it with planetary velocity from without. The 
intruder is instantly surrounded with a fiery envelope heated 
to the greatest conceivable intensity; its surface is burned off 
or dissipated|into vapor; the sudden expansion of the stratum 
immediately beneath the burning surface tears the body into 
fragments, each of which, retaining its planetary velocity, is 
instantly surrounded by a similar envelope, which produces 
like effects, and so on until, in most cases, the whole is burned 
up or vaporized.” A second paper on the same subject, and 
of similar import, was published by Mr. Marsh in the Pro¬ 
ceedings of the American Philosophical Society, vol. XIV, 
114. 
From an examination of the list of November meteor 
showers from A. D. 902 to A. D. 1833 Prof. H. A. Newton 1 
concluded that “ the star-shower has a motion along the 
sidereal year of one day in seventy years, and also that the 
shower has a period of about a third of a century. This 
precession seems to imply that the orbit of the body furnish¬ 
ing these meteors has only a small inclination to the ecliptic, 
and that the motion is retrograde. The small distance of 
the radiant from the point to which the earth is moving, 
viz., 7°, confirms this conclusion.” 
In an article on the peculiarities of the November meteors, 
Prof. H. A. Newton 2 arrived at the following conclusions: 
“ The length of the annual period as determined from the 
showers in A. D. 902 and 1833, reckoning 233 leap years, 
19 odd days, and adding six hours for difference of longi¬ 
tude, is 365 + ( 233 ^J 9 ' 25 ) ? Qr 365.271 days. The length of the 
cycle is 33.25 years. 
“ The length of the part of a cycle during which showers 
may be expected may be five or six years or, for extraordi¬ 
nary displays, at least 2.25 years. The supposition of a 
ring of uniform density throughout its circuit seems im¬ 
probable. 
1 A. J. S., XXXVI,, 300. 
2 A. J. S., XXXVIII,, 53. 
