( 10 ) 

 V. Table of ULagmfymg Powers. 



OBJEC- 

 TIVES. 



EYE-PIECES. 



Beck's 1, 

 Powell's 1, 

 Ross's A, 



2 



10 j 



13i 



15 



20 



25 



30 



33i; 



40 



50 



60 



70 



80 



90 

 100 

 110 

 120 

 130 

 140 

 150 

 160 

 170 

 180 

 190 

 200 ! 

 250 

 300 

 400 

 500 I 

 600 i 

 800 i" 



Beck's 2, 

 Powell's 2, 



and 

 Ross's B, 

 nearly.* 



Powell's 3. 



Ross's C. 



Beck's 3. 



Beck's 4, 

 Powell's 4, 

 Ross's D. 



Beck's 5, T)„„„,,i„ c 

 Ross'6E:1P°^«*1«5- 



Ross's F. 



Focal Length. 



2ii 



n 



lii 



4 • 1 • 



xlyin. I 3 in. 



Magxiftixg Power. 



'2 



10 



m 



15 



20 



25 



30 



AMPLIFICATION OF OBJECTIVES AND EYE-PIECES 

 COMBINED. 



10 



16| 



25 



33i 



50 



C2i 



• 65| 



75 



100 



125 



150 



166-1 



200 



250 



300 



350 



400 



450 



500 



550 



GOO 



€50 



700 



750 



800 



850 



900 



950 



1000 



1250 



15(10 



2000 



2500 



3000 



40f'0 



15 



18| 



25 



37^ 



50 



75 



93f 



100 



112§ 



150 



1871 



225" 



250 



300 



375 



450 



.525 



600 



075 



750 



825 



900 



975 



1050 



1125 



1200 



1275 



1350 



1425 



1500 



1875 



2250 



3000 



3750 



4500 



6000 



40 

 50 

 6Gf 



100 



133^ 



200 



250 



2fiS| 



300 



400 



500 



600 



666| 



800 

 1000 

 1200 

 1400 

 1600 

 ISOO 

 2000 

 2200 

 2400 

 2600 

 2800 

 3000 

 3200 

 3400 

 3600 

 3800 

 4000 

 5000 

 6000 

 8000 

 10000 S 

 12000 I 

 16000 



50 

 621 



125 



166| 



250 



3121 



3H3i 



.375 



500 



625 



750 



833^ 



1000 



1250 



1.000 



1750 



2000 



2250 



2500 



2750 



3000 



3250 



3500 



3750 



4000 



4250 



4500 



4750 



5000 



6250 



7500 



10000 



12500 



15O0O 



20000 



60 



75 



100 



150 



200 



300 



375 



400 



450 



600 



750 



900 



1000 



1200 



1500 



1800 



2100 



2400 



2700 



SOOO 



3300 



3600 



3900 



4200 



4500 



4800 



5100 



5400 



5700 



6000 



7500 



9000 



12000 



15000 



18000 



24000 



* Powoll and Lpaland's No. 2 = 7-4, anil B'«k'» No. 2 and Ro.fs's (i = 8 mngnifying power, or 

 resjiectively ,V Icm anJ/j^ more tliun tlie flgiires givnn in this column. ' 



