B. V. Marsh on the Distinguishing Features of Comets. 97 
illuminated column several miles in diameter and five or or six 
hundred miles in length, which originating in the upper portions 
of the atmosphere pecjecte itself far beyond its limits, and whilst 
tevolving about the magnetic axis of the earth maintains its 
rectilinear form. Now it can scarely be doubted that these are 
electrical currents, and as the visibility of such currents is be- 
lieved to be due solely to the presence of illuminated matter, we 
must conclude that the auroral streamer carrie’ up from the 
atm = ens of matter, its illumination of which shows 
its position. This, of itself, is not a matter of surprise, because 
the Beancet: of Pi cker and Gassiot have neibee coe shown 
that electrical currents are not only capable of transport: 
ing particles of peice but that even the hardest metals are 
unable to resist them. Ina recent series of experiments upon 
electric discharges in vacuo, Mr. Gassiot has shown that with 
went various modifications as the night progressed. When first observed, it was 
nearly ¢ me edit with respect to the comet’s axis. The eastern wing was per 
pias alittle the longer of the two, songs Pi was a dark oval spot near the middle 
0: e a litt 
x m. pre 
trata, each with a cusp on either side. Afterwards the lines appeared bro 
giving a mottled appearance to the central zone of the sector, and finally the one 
Sunpe - ae 
to bre ace was transformed ana a spiral whose 
ry Was in th nwhile, the hours of : , the ne 
red Mi et Rats " st double of the Srigyind size, W 
this whole mass “iad § increased to “at Ie A ae ; a. diffcalty the ge Pee 
thape eould be recognized.” 
ae was Page st ees Baran as brilliant as during last night, nor was the dark ce 
ne n 
Which periods the thse of ii ht sometimes seemed wholly ome to within 12° 
a3 a sah br ahok be ° the bril- 
abe great volume wr Siete s within 10° of the nucleus, oe sa ace 
linge e , wes 
_n acy of the coma did not Mhload: that of the — ei ae ‘ow from eealens in 
0 distin ret 
pe pre de sen nee to pairs A a degree be bd Bootis "Dirt ring t was 
de, b at 
Ted Comets si te the Ni fort b British ‘evi f for sires aire’, Foi 
ter 0 > contains the following which seems strongly to confirm the electri 
nn Phenomena : 
of mate can be no doubt, that sudden changes of brightn tnese, and slower changes 
f1agnitude, take place in comets, Kepler er informs us that the 
Snellius an 
the on alate saw similar movements in §, shdalations Ske 
hem, aurora, the tail ccmetiid covering certain reanvegte . 
f sate Seta here oe von rel nog the the eye of the ar sli a “s 
Pgnin in Halle fact oe that the nucleus, the whole 
or part of the “ebay, ~ lie dig aps “gs comet, may exhibit almost instantaneous 
of brighta . 274, 
Aw Jour. Scr.—Szcoxp Serres, Vou. XXXII, No. 97.—Jax., 1862. 
13 
