id 
P 
AMERICAN @ 
JOURNAL OF SCIENCE AND ARTS. 
[SECOND SERIES.] 
Art. I.—On the erence of « Normal Map of the Solar Spec- 
trum. Epo abstract of a memoir read before the National Acad- 
of Sciences, Aug. 7t th, "18 66; by Wotcorr GrBBs, = 
lversity. . 
-RanMord Professor i in Harvard Uni 
ee 
THE detriocdinaty impulse which has ven to the ee 
‘ been gi 
of the spectrum by the investigations of Bunsen and Kirchho 
has led to an accumulation of details which have not yet been 
systematically or even conveniently arranged. To a certain ex- 
tent at least this has arisen from the sin of a standard map of 
the solar spectrum upon which new lines may be entered with 
precision as regards their relative places. The well known 
of Kirchhoff, though executed with great care and labor, is not, 
properly § speaking, normal, since it only represents a spectrum 
rmed by four flint glass prisms, the angles of which, it is pie . 
are given, but of which the indices of refraction are ‘not stated. 
their positions. Such a map can only be oe 
— we the ae lines, since these do n 
