137 
an Iconantidiptic Telefcope. 
fhe numerical application of the particular cafe of the 
equal lenfes a and c. 
Ft. In. 
Let AD=F=i7a8 lines, = 12 o 
<3 , b=o,236i f =408 lines, a 10 
Then we ab=o,5278f= 9I2 lines, 6 4 
Ihallhave ^a=o, 7639F = 1320 lines, 9 a 
(#d=#b + bd=i, 7639F = 3048 lines, 21 2 
It is from this particular cafe, in which <p=f and 
/= fx N /5~2=o, 23607 F, that the following table is 
conftru&ed. 
application numtrique du cas par ticulier des lent ilia egaks a et c, 
P. P. 
Soit ad :=f — 1728 lignes zz ia o 
"gb = 0,236 1 f 1= 408 lignes, a 10 
ab = 0,5278 f = 912 lignes, 6 4 
tfA z: 0,7639 F =z 1320 lignes, 9 2 
j?d =ab + bdz 1*7639 f = 3048 lignes, 21 2 
Ceft d’apres ce cas particulier, ou Ton fuppofe 9 — /» et que /«F (1/5 — 2) ~ 
0,23607 f, qu’eftconftruitela table qui fuit. 
Alors on aura « 
Vol. LXIX. 
T 
Focal 
