Nystrom, John W. (John William), 1824-1885 · Philadelphia, J.B. Lippincott · leaf 327
316 Double Convex Lens. f= + ^r . the principal (m-l)(J?+r)* focal distance. o *= optical centre of the lens. … 317 Piano Convex Lens. /= + m—1 The optical centre is in the convexsurface.
Mechanical engineering · Engineering
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