Talking to the Computer: A Prototype Speech Recognition System for Early Reading Instruction. Report No. 91-3.

Urological endoscopic instruments known before this invention do not permit continuous clear vision of the operative field because such vision is periodically obscured by the turbid fluid produced at the operative field. The invention produces continuous clear vision of the operative field by causing continuous inflow of clear irrigating fluid to the operative field and continuous outflow of turbid fluid from the operative field, thus providing a continuously flowing system which is provided by two conduits, one for inflowing clear fluid having its outflow port within the beak of the sheath and below and in front of the objective lens of the telescope which forms part of the instrument, and one for turbid outflowing fluid from the operative field having its inlet port in the exterior of the sheath above the objective lens and to the rear of the beak, so that the inflowing clear fluid must pass through the operative field to reach the inlet port of the outflow conduit, the outflow of fluid being maintained by suction applied to the outflow conduit.