PETROGRAPHIC MICROSCOPE
MODEL: 'NEW PETROLOGICAL' or 'DICK PETROLOGICAL'(Objectives)
MAKER: JAMES SWIFT & SON
c. 1900
SERIAL NUMBER: 10829
The objectives are a J. Swift & Son 1 inch, a J. Swift & Son 1/4 inch with n.a. 0.88, and a 1/12 inch J. Swift & Son oil immersion with n.a. of 1.30. The objectives each come in their own can, each labeled 1 IN, 1/4 IN, and 1/12 IN respectively. Swift offered two different 1/4 inch objectives one with n.a. of 0.80 and the one seen here with the higher n.a. of 0.88 which made observation of conuscopic figures easier.
