| 摘要 |
A microfiche reader in which the subject to be viewed and by which any selected area thereof can be quickly and easily brought into intersecting alignment with the light beam of the optical system of the machine, is carried by the upper one of two superimposed rigid frames that are mounted on the base of the machine by elongated ball bearing retainers interposed between stationary tracks fixed to the machine base and endwise movable tracks fixed to the lower one of the superimposed rigid frames, for movement in unison across the machine base along one of a pair of coordinate horizontal axes, and connected with one another for relative movement along the other one of said axes by similar elongated ball bearing retainers having rolling engagement with upper and lower tracks respectively fixed to the upper and lower rigid frames.
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