lard 
5 ‘ 9 [Frazer. 
acters of the skull. What he called incisors are canines; and the 
large horns are not on the frontals, but on maxiliaries. The top of 
the skull moreover is not convex, but concave, and the occiput is 
oblique, and not vertical. Prof. Marsh stated that he had described 
several species of this group, one of the most singular of which, Dinoceras 
mirabilis, Marsh, was represented in the Museum of Yale College by 
a nearly perfect skeleton, and portions of several others. In all of 
the species the limb bones differ considerably from those of Probos- 
cidians, while the skull is so totally unlike anything hitherto known, 
that he could not refer these extinct animals to that group, and hence 
had proposed for their reception the order Dinocerea. 
ON A SPECTROSCOPIC OBSERVATION OF THE AURORA OF 
APRIL 10, 1872. , 
By PrerstFror FRAZER, JR. 
(Read before the American Philosophical Society, April 19, 1872.) 
On the night of April 10, 1872, a very beautiful Aurora was seen from 
Philadelphia, spreading over 25° or 30° of the Northern Heavens. 
The night was clear, and the wind was from N. W. and slightly cool. 
A heavy bank of cloud covered about one-sixth of the horizon to the 
north, and from the crest of this bank the Aurora seemed to proceed, 
shooting up fitfully in sprays and bundles to near the zenith, and travers- 
ing from west to east and back again with average rapidity. One de- 
tached streamer crossed the zenith from N. E. to 8. W., and remained 
permanent in position, giving only occasional fluctuations of light. 
Observations were commenced with a Browning angle measuring spec- 
troscope, the light condensed through a 18 foot focus, 9 in. diam. lens. 
The observations were made solely with reference to the green line in 
the Aurora, and the purpose in view was to verify or not the observations 
of Piazzi Smith in regard to its coincidence with the green hydro-carbon 
line seen at the base of every candle and illuminating gas-flame. 
Four observations gave the following results : 
dicaGineen linen Of AUN OT As. htc. vie 00! os cece ein eS bbl 0/1 
2, “ ee ee 92°. .35/ 017 
3. “6 ut Fe ee ae DOL es be cet DOSk AB O 
4, ““ 66 os a 5a eds aad tas le gle age meee ae 929 20’ 0” 
The line became exceedingly faint during the 8d and 4th observations 
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