Huyghenian Construction of the following magnifying powers on a 6-1/2
feet focus object-glass:—
£ s. d.
35, 60, 90, 130, 180, 200 each 0 15 0
320, 450 1 1 0
610 1 7 6
All fitted with Sunshades.
Improved Achromatic, Ramsden’s Construction.
£ s. d.
90, 130 each 1 0 0
189, 250 1 10 0
320, 450 1 12 6
610, 750 1 15 0
850 2 2 0
Kellner’s Construction.
£ s. d.
30, 58, and 80 each 1 5 0