32 Refracted and Diffracted Spectra. (January, 
To fina 2 — 
log. £ 3°3787975 
p € 3°2857 
oe = 1'2390 Ae Sees 
‘i 99°73 9°0930975 
to find ze log. of log. x 0°1093490 
log. of ¢ 0°5166279 
log. xe 4°2264610 0°6259769 
p 
1239075 _~— log. g 3°0357948 
Ze 
log. x, above 4°2264610 
4 =0'064466 teh 2 YB Bogs sae 
—— log. r3°5413296 
P4%— 17303541 log. o°1151247 
ze XE ee BK 
log. yé=3°4262049 log. 0°5348133 
log. € 0°5166279 
log. y =1°0427624 o°0181854 
add constant 2°5947234 
¥=4339°96 3°6374858 
According to Angstrom, the value of this wave- 
length.in the millimetric. scale is. . ... . « 4S4Ge 
According to the above itis .° 2°. > 3.65. Se 4gapae 
Difference 0000°14 
which is almost unappreciable. 
‘In judging of this result, it must be borne in mind that 
the chances of errors of observation, in ascertaining the 
wave-length and the position of the line in the scale of the 
spectroscope, are about equal; so that, of the above dif- 
ference, small as it is, only one-half should be set down to 
the wave-length. If the latter be made 4340°03, thus 
halving the difference, then with the exponent «=3°2857, 
the position of the line in the scale of the spectroscope 
would have to be made 2796'56, which differs only oo000°r4 
from that assigned to it by observation—a difference which 
is in like manner scarcely appreciable. As determined by 
the table, then, this hydrogen line ought to have for its 
index position 2796'56, and for its wave-length 4340°03. 
