with complete Color Correction. 431 
are included the seven of Fraunhofer,* viz: 
Flint 23,. -- 
six of Van der Willigent (one closely resembles my A above, 
while two others are almost exactly alike), viz: 
srt Merz No. III, 
and finally one of Ditscheiner,t 
There are Sones measurements of 18 ‘iferent prisms by 
Dutiron,§ but so inaccurate as to be worthless for our purpose. 
n the order in which the glasses are named are entered in 
table I, the values of the constants for (8). 
TABLE I. . 
A, gi8 i a 
a + 0 +r + 0 
B 22°3186075 —29°1759937 10°2399102 
Y 14-0097123 —17°9513549 . 6°4320057 
6 5679958 + 2172063 2631091 
e 21-026827 —27-430617 
¢ 5749543 + 2333290 259890 
2 9025943 — 2110704 411148 
t 52924649 — 6°1318968 2°4193199 
t 19°6074744 —25-7440377T 91597811 
ik 20°7768050 —27-0625275 9°5093547 
A 24-6152640 —32°2820439 112916241 
ra 25-4950932 —33°4611946 11°688423 
v 2-250818 — 1°973145 0°983738 
iy 2°737385 — 2679993. 1:241673 
° 19°541685 —25°438209 8976709 
7 27°444400 —36°035067 12°537277 
p 43623628 —57°822556 19°899438 
o 69°141334 —91°827575 31°313410 
T 19°960275 — 26041640 9°196286 
* Schumache s Astronomische Abhandlung fiir 1823. 
+ Archives = (F2 usée Teyler. 
Coo sledel der = k Akad. d. Wissenschaften in Wien. Oct., 
Comptes Rend 
us, ee Poggend. Annal., ix, oe 335-336, 
de Ch himie, eae i bes 176-21 These incredible values, which are 
extensively pore in prominent text oer on optics, have given me a deal of 
trouble, used as th fu sev 3 to discuss the defects Aa poate 
inibeovoment of the double objective. Only by the me ance I found on the 
eg ! himie, nis, PP. e 502, a set of corrections 
