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$94. «=——s PROCEEDINGS OF THE SECTIONS. 
movements were the subject of a classical memoir by the iThustiions 
Bessel. Delambre, in his Astronomie Théo et Pratique, tome 
aii, says that the paid lies between 1403-6 Sand 2157-4 years, and 
that the perturbations will produce great changes in the elements, 
principally i in the time of revolution. In fact, the length of the 
period is almost the only circumstance that militates 
against the supposition of the identity of this comet with that 
which visited us in May and June last. We must, however, bear 
mind that observations taken in the beginning of the present 
Aelita are not so accurate as those now made by astronomers. 
In support of my remarks on the non-identity of our late visitor 
with the Comets IT, 1819, II, 1861, and on its probable identity 
with that of 1807, I here give the orbit-elements of the three 
comets for comparison with those I have deduced. The elements 
of Comet II, 1819, and of Comet 1807 are by Brinkley and Bessel 
respectively, and those of Comet IT, 1861, are’from Dr. Heinrich 
Kreutz’s definitive investigation, a copy of which elaborate work 
he iteoac sent to me some months ago. 
Comet II, 1819, Comet II, 1x61. © Comet, 1807. 
Perihelion passage, G.M.T. ........ June 27d. 17h June 11d. 12h. Sept. 18d. 18h. 
Longitude of perihelion .......... 7° 57’ 249° 21’ 271° 57’ 
Longitude of ascending node...... 279 15 267 49 
Inclination of the orbit 80 46 ” $5 26 63 10 
Periheli on distance te ny: 0°3410 93% 06461, 
_ The longitudes are roughly corrected for the’ p precesion of the 
equinoxes since the respective epochs. Remarkable as our late 
visitor is in connection with its supposed identity with the comet 
of 1807, it is perhaps quite as remarkable in another respect. 
_ The fact is the earth has had an exceedingly narrow escape 
nd, Ss 
comet from the sun and earth were respectively eighty-two and 
seventy-one millions of miles. For some days the eae and — 
at the time pointed out, were rapidly approachin 
o'clock in the afternoon of June 16th, Sydney ck the comet 
passed through perihelion at a distance of sixt sixty-nin as 
miles from the sun, and at eighteen minutes past 7 o'clock “bit at be 
_ afternoon of the 19th it reached the plane of the eo ea pe 
_ the ascending node. On at the elements before ; iad Ae 
oo will be seen that the longitude o: the node is 270° 37’, ani I ee 
_ that the heliocentric longitude of the earth at ‘the se 5 es) 
mk in 9’, so it follows on the assumption that the comet 
- Pointed directly from the sun that, the earth, had she be? 
