of Achromatic Object-Glasses . 819 
proportion ; but it is sufficiently accurate for any practical pur- 
pose. 
TABLE — Shewing the Radii of * the 1st and 4th Surfaces of 
Object-Glasses to various dispersive ratios , and to Indices of 
Refraction 1.524 Plate , and 1.585 Flinty with Columns of 
Correction for other Indices . 
1st Surface . 
4th Surface . 
Dispersive 
Radius to 
Radius to 
Ratios. 
Indices 
Correction, 
Correction, 
Indices 
Correction, 
Correction, 
Flint Index. 
1*524 
1*585 
Plate Index. 
Flint Index. 
1*524 
1*585 
Plate Index. 
•550 
6*7185 
+ 7-40 
_ -110 
14*5353 
4 * 100-00 
— 50*33 
•551 
6*7182 
+ 7-39 
— -100 
14*5303 
4 - 100-99 
— 50*45 
•552 
6-7179 
+ 7-37 
_ -090 
14-5253 
4 - 101-18 
_ 50-58 
•553 
6*7176 
+ 7-36 
— *080 
14*5203 
4 * 101-37 
— 50-70 
•554 
6-7173 
4 - 7*34 
_ -071 
14*5153 
+ 101-57 
— 50.83 
•555 
6*7170 
+ 7-33 
_ *062 
14*5103 
+ 101-77 
— 50-95 
•55 6 
6*7167 
+ 7*31 
_ -052 
14*5053 
+ 101-96 
— 51-08 
♦557 
6*7164 
+ 7-30 
_ *042 
14*5003 
+ 102-15 
— 51-21 
•558 
6*7161 
+ 7*28 
— -032 
14*4953 
4 - 102-34 
— 51-33 
*559 
6*7158 
+ 7*27 
— -023 
14-4905 
4 - 102-54 
— 51-45 
•560 
6*7155 
+ 7-25 
_ -014 
14*4857 
4 - 102-74 
- 51-58 
•561 
6*7152 
+ 7-24 
— -004 
14-4809 
4 * 102-93 
— 51-70 
•562 
6*7149 
+ 7-22 
4 - -006 
14*4761 
4 * 103-12 
— 51-83 
•563 
6-7146 
+ 7-21 
4 * '016 
14-4713 
4 - 103-31 
— 51-95 
•564 
6-7143 
+ 7'19 
+ -025 
14-4665 
4 - 103-51 
— 52-08 
•565 
6*7140 
+ 7-18 
4 - *034 
14-4617 
+ 103-71 
— 52-20 
•566 
6*7137 
+ 7-16 
4 * -044 
14-4569 
+ 103-90 
— 52-33 
•567 
6-7135 
4 - 7*15 
+ *054 
14-4521 
+ 104-09 
— 52-45 
•568 
6*7133 
+ 7-13 
4 - -064 
14*4473 
+ 104-28 
— 52-58 
•569 
6-7131 
+ 7-12 
4 - -073 
14-4425 
4 * 104-48 
— 52-70 
•570 
6-7129 
+ 7-10 
4 - -082 
14-4377 
4 - 104-68 
— 52-83 
•571 
6-7127 
+ 7-09 
4 - *092 
14-4329 
4 * 104-87 
— 52-95 
•572 
6*7125 
+ 7-07 
4 - *102 
14-4281 
4 - 105-06 
— 53-08 
'573 
6-7123 
- 4 - 7-06 
4 - -112 
14-4233 
4 - 105-25 
— 53-20 
•574 
6*7121 
+ 7-04 
+ -121 
14-4185 
4 - 105-44 
— 53.33 
•575 
6-7119 
+ 7-03 
4 - -130 
14*4137 
4 - 105-64 
— 53-45 
•576 
6-7117 
+ 7-01 
4 - *140 
14-4089 
+ 105-84 
— 53-58 
•577 
6.7115 
+ 7*00 
4 * -150 
14*4041 
4 - 106-03 
— 53-70 
•578 
6.7113 
+ 6*98 
4 * *160 
14*3993 
+ 106-22 
— 53-83 
•579 
6-7111 
+ 6-97 
4 - *169 
1 - 4*3945 
+ 106-41 
— 53-95 
•580 
6-7109 
+ 6-96 
4 - -178 
14-3897 
4 - 106-61 
— 54-08 
•581 
6‘7107 
+ 6-95 
+ *188 
14-3849 
4 - 106-81 
— 54-20 
•582 
6-7105 
4 - 6-94 
4 - -198 
14-3701 
+ 107-00 
— 54-33 
•583 
6-7103 
4 - 6-93 
-208 
14*3753 
+ 107.19 
— 54-45 
•584 
6-7101 
+ 6-92 
4 - -217 
14*3705 
+ 107*38 
— 54-58 
•585 
6*7099 
+ 6-91 
4 - *226 
14*3657 
4 - 107-58 
— 54-70 
•586 
6-7097 
4 - 6-90 
4 - -236 
14-3609 
4 - 107*78 
— 54-83 
•587 
6-7095 
4 - 6.89 
4 - -246 
14*3561 
4 - 107-97 
— 54-95 
•588 
6-7093 
+ 6-88 
+ -256 
14-3513 
4 - 108-16 
— 55-08 
•589 
6*7091 
4 - 6-87 
4 - -265 
14-3465 
4 - 108-35 
— 55-20 
