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spherules, supposing the least distance of distinct vision to be 7 inches, and the object to be placed (l) at the focus, (2) at the least distance for distinct vision.

Focal length
in terms of
an inch. No. of times that the
length of the object
is magnified. No. of times that
the surface is
magnified. —————— —————— —————— —————— —————— .10 007.00 008.00 000049 000064 .75 009.33 010.33 000087 000107 .50 014.00 015.00 000196 000225 .40 017.50 018.50 000306 000342 .30 023.33 024.33 000544 000592 .20 035.00 036.00 001225 001296 .15 046.66 047.66 002181 002276 .10 070.00 071.00 004900 005401 .05 140.00 141.00 019600 019881 .03 233.33 234.33 054289 054912 .02 350.00 351.00 122500 123201 .01 700.00 701.00 490000 491401

The next Table is for a person whose least distance of correct vision is 5 inches.

Focal length
in terms of
an inch. No. of times that
the length
is magnified. No. of times that
the surface is
magnified. —————— —————— —————— —————— —————— .10 005.00 006.00 000025 000036 .75 006.67 007.67 000044 000058 .50 010.00 011.00 000100 000121 .40 012.50 013.50 000156 000195 .30 016.67 017.67 000278 000312 .20 025.60 026.00 000625 000676 .15 033.33 034.33 001111 001179 .10 050.00 051.00 002500 002601 .05 100.00 101.00 010000 010201 .03 166.67 167.67 027779 028110 .02 250.00 251.00 062500 062901 .01 500.00 501.00 250000 251001