586,936. Photo-electric apparatus for examining transparent vessels. UNITED DAIRIES, Ltd., and STOATE, N. P. Sept. 19, 1944, No. 17881. [Class 40 (iii)] In apparatus for scanning the bottom of a transparent vessel to detect foreign bodies thereon by means of a light beam directed longitudinally through the mouth and bottom of the vessel towards a light-sensitive device, the vessel is rotated about its longitudinal axis relative to a scanning device comprising a first screen provided with an aperture having an area small relative to that of the bottom of the vessel and a second screen provided with a slit which is disposed substantially radially of the bottom of the vessel in the scanning position in combination with means for moving the first screen relatively to the second screen to traverse the aperture along the slit as the vessel rotates. The general construction and operation, apart from the scanning function, are mainly similar to the arrangement described. in Specification 586,935. The. bottles are supported on platforms 6 mounted in a rotating head 5 and each platform has an arcuate slit 11 corresponding to the radius of the bottle. An aperture 31 in a pivoted link 26 is traversed along the slit while the bottle is rotated on its longitudinal axis by engagement with a flexible band as described in Specification 586,938. The position of the link 26 is varied by a pivoted rod 27 having a roller 34 which engages with a fixed cam 35 having a stepped contour. In a modification, Figs. 5 and 7, the platform is formed by a sheet 6a of clear glass and forms the top of a compartment housing a tubular screen 65 with a slit 66 extending radially of the platform. The photo-electric cell 13 is enclosed within a second tubular screen 71 having, a small aperture 72 which is traversed along the slit by a rod 68 attached to the casing 71 and held in engagement with a fixed stepped cam 74 by a spring 75 engaging an abutment 69 on the rotating head 5 and a collar 76 on the rod. The slit 11 may be of varying width, Figs. 9, 10 (not shown) with its maximum width equal to the diameter of the aperture 31. Specification 586,939 also is referred to.