Abstract: The telescope of the level-transit includes two mirrors at 45.degree. to the light path. A first mirror is fixed in the telescope housing by screws which thread into the mirror support to pull it tight against a datum surface established by a cover. The other mirror is mounted for pendulating action to automatically compensate the instrument for deviation from level within the design range. When the instrument is used as a transit the telescope is free to tilt up and down to measure vertical angles. At that time the pendulum is locked in center position. When the instrument is used as a level, the telescope is locked against elevation or depression. The locking mechanism actuates a device which frees the pendulum for operation to automatically compensate the level. The bottom of the pendulum weight has an inverted conical member fixed therein. The conical portion passes through an elongated hole in a leaf spring fixed in the telescope to flex about an axis transverse the mirror pivot axis.

Abstract: Each embodiment has a linear bearing member having a ball retainer captured in the member to retain the ball bearings when the opposing bearing member is removed from the assembly. In one embodiment the opposing member has a race resting on the balls. In the other embodiment the first member has upper and lower races and the retainer holds ball bearings against each while the opposing bearing member fits between the upper and lower balls and has upper and lower races cooperating with the balls so the opposing member can be loaded upwardly or downwardly and still run on balls.

Abstract: The microfiche reader has two lenses carried by a segment mounted on an eccentric pivot which can be adjusted to move the pivot and, therefore, the lenses are in an eliptical orbit which permits the lens in the operative position to be centered on the optical path. When the segment is shifted to move the other lens into position that lens will be centered. Each lens is focused by moving the associated focusing slide in and out to move the parallel cams under the bosses carried by the lens barrel flange to raise and lower the lens to focus the image. The image is centered on the screen by adjusting the first mirror which is mounted on a bracket which pivots on a housing partition and has a wedge between the bracket and the partition. The bracket has teeth which engage serrations on the wedge so when the retaining screw is tightened the wedge is locked in place.

Abstract: The microfiche carrier slides laterally on front and rear ball bearings between the carrier and subcarrier. The front bearing permits vertical separation of the carrier from the subcarrier and the rear ball bearing then permits the race member carried by the carrier to be withdrawn from between the upper and lower sets of ball bearings. In use the carrier is latched to the subcarrier by a latch carried by the transparent index pressure plate. The subcarrier is mounted on the base by ball bearings. The base contains the electrical components and the light source and condenser lens. The base can be withdrawn from the housing as a unit with the carrier attached.

Abstract: The film image is illuminated by the bulb or by ambient light admitted through an aperture on the top of the viewer. The image is projected on a folded light path onto a screen pivotally mounted on the underside of the upper housing to depend into the viewing chamber in the lower housing. The lower housing is pivotally connected to the upper housing and contains a power mirror reflecting the image on the screen into the eyes of the user. When the lower housing is folded (collapsed) over the upper housing the screen pivots into the space between the housings. The screen pivot is moveable to change the screen distance from the power mirror (and the film stage), to adjust the toe-in required of the viewers' eyes for optimism viewing comfort. The microfiche carrier mechanism is generally U-shaped to straddle the light path to the film stage and is positively driven back and forth relative to the housing film stage and engages the fiche on each side of the light path to move the fiche laterally.

Abstract: The microfiche projector enlarges the image onto the flat white undersurface of the top panel of the enclosure which has a flat black interior. The viewer sees the image reflected in the adjustable 45.degree. mirror. The apparent image is about 50" in front of the user to reduce eye fatigue. The image is non-directional which allows considerable movement of the user.

Abstract: There is disclosed herein apparatus for positioning rows and columns of microimage frames imprinted on a cassetted filmstrip for projection and display. The filmstrip is longitudinally movable in incremental amounts through an elongated cassette passageway, the passageway having a transverse aperture for permitting projected light to pass through a selected portion of the filmstrip for enlarged and focused microimage display.

Abstract: The portable projector has a drawer which is pulled forward for use and to gain access to the opal glass rear projection screen which is inserted into the slot in the front of the drawer. The projection lens is removed from its storage compartment in the drawer and threaded into the optical housing after it has been pivoted to its upright position. A selected microfiche is inserted in the slot between the optical housing and the lensboard and is retained in selected position by friction from velour facings in the slot. The bulb is low voltage, low power to permit use of battery power or line voltage through a transformer. If the opal glass is not used, the image can be projected on a light colored surface within the limitations of the bulb intensity and ambient light.

Abstract: The optical sighting instrument uses the image of a floating bubble in a spirit level as a self-compensating index mark to indicate a reference line of sight at a given angle to the earth's normal surface.

Abstract: The microfiche card has micro images arranged in horizontal rows and vertical columns. The card is inserted into the slots at the fronts of the sides of the housing and can be moved to align the desired column with the lens. The lens is vertically movable on the front of the housing and can be aligned with the desired row of images. The back of the housing has a light gathering lenticular panel which transmits light into the light chamber where it is diffused and illuminates the light diffusing (Opal) glass and the micro image. Under low ambient light conditions the switch on the handle may be depressed to illuminate the bulb in the light chamber. The handle houses the batteries which power the bulb. The focal length of the ocular is selected to provide the proper magnification of the image to make the image readable.