seetniaL, Seoe EEO. of Immersion Lenses. 139 
TABLE III. 
DEVIATION. 
| 
REFRACTION BETWEEN Fiint Giass 
REFRACTION BETWEEN HeEAvy FLINT | ean 
care AND PLATE GLASS.* ene - AND CANADA BALSAM. 
a = -| through rarer == a 
¢’ Deviation. medium. Deviation. ¢’ 
(e) ' fe) ! fe) | (eo) ! (e) ! 
0 50 OF 20 1 0 1 OND 
1 40 0 20 2 ( IL ays: 
2 30 0 30 3 Ons 7 aT 
2 20 0 40 4 Onee Ss 33) OE, 
4 10 0 50 5 One4G 4 54 
8 21 E39 10 0 13 Se. 
17} Bil 2 29 15 OFS 14 41 
16 38 3 22 20 0 26 1) 
20 43 4 17 25 0 33 24 27 
24 44 5 16 30 0 41 29) 19 
32 «633 Te ZAG. 40 0 59 39 1-5 
st] G3 110) Soe 7/ 50 11) 8: 48 37 
46 28 13 32 60 I atsicry ieh 1 / dl 
Sl ay 18 8 70 or ok 66 59 
ay ay 24 28 80 a il7/ 74 43 
56 30 Fas) 85 7 38 th 22 
56 50 oe LO 90 i S57/ 78 23 
Angle of Refraction.| Deviation. Deviation. | Angle of Refraction. 
Another substance may be used for immersion lenses—turpentine 
—whose refractive index + is nearly equal to that of Canada balsam. 
Taking flint glass at 1°576, 
1°545 
1-576 
and tabulating a few values for deviation it will be found when the 
objective is immersed in turpentine :— 
Sin. ¢’ = sin. ¢ = 98033 sin. ¢, 
TABLE IV. 
| mai | 
Angle of Refraction On }iquity @ of Ray ad 
TaptIneSeatae | entering Objective. Deviations. 
Oo ! eo) fe} ! 
@ 6) 1 (al 
4 54 3) OVnG 
9 48 10 0 12 
19 35 20 0 25 
39 «64 40 0 56 
58 6 60 g ga 
74 54 80 DP eG 
78 37 90 Tis 
* Plate glass w = 1°500. Heavy flint glass « = 1-791, highly refractive. 
+ Refractive index: Turpentine, 1°545; C. balsam, 1°532. 
