SCIENTIFIC SUMMARY. 
ASTRONOMY. 
I N our summary for January, it was recorded that Professor Adams liad 
seen reason to doubt the correctness of the period assigned by Professor 
Newton to the November meteor-ring. The rigid mathematical scrutiny of 
the nodal motion due to the actions of Venus, Jupiter, and the Earth — the 
planets which would be the principal perturbers of the meteoric Orbit on 
Newton’s hypothesis — has resulted in showing that 354-6 days is not the 
true period of the orbit. In like manner a period of 377 days — another 
view suggested by Newton — must be abandoned. Either theory gives to the 
node an annual motion of about 2F', whereas to account for the observed 
change in the epoch at which the November shower occurs, a motion of 
52 // *4 is required. 
It remained to calculate the motion of the node when a period of 33*25 
years is selected — that being the only other period, besides those considered, 
which fairly accounts for the interval observed to separate successive 
recurrences of brilliant meteoric displays. This period, which gives (by 
Kepler’s law) an elliptic orbit, having a major axis 20*7 times as great as 
the earth’s distance from the sun, presents many difficulties. The formulae 
adapted to the nearly circular planetary orbits are here inapplicable. Adams 
applied the method given by Gauss in his “ Determinatio Attractionis, &c.” 
In this method the long ellipse is broken up into small parts, and the 
perturbing effects of the planets on the motion of a meteor in each part is 
considered, the change in the node as the meteors move over each section 
being separately examined. The calculation is very laborious, though 
Professor Adams simplified the work to some extent by introducing several 
ingenious modifications. He found that during a period of 33*25 years the 
longitude of the node is increased 20' by the action of Jupiter, nearly 7 ' by 
the action of Saturn, and about 1' by that of Uranus. The other planets 
produce no appreciable perturbations. Thus the observed increase of 
longitude is about 28' in 33*25 years, or 50"*2 in one year. We have 
already stated that the observed motion of the node is 52 // *4. The accordance 
is close enough to leave no doubt that the true period of the November 
meteors is 33*25 years. 
This result very largely enhances the interest with which the phenomenon 
of periodic November displays must be viewed. On Newton’s hypothesis 
one could understand the recurrence of brilliant showers during two or three 
successive years ; since the earth was assumed to pass for two or three years 
in succession through parts of the ring not very far separated from each other. 
But with meteors travelling in an elongated ellipse, extending beyond the 
