Abstract: A rotor having N and S poles is rotatively supported through bearings from the lower end of an electrode to be immersed in a water sample in which dissolved oxygen is measured. A rotor driving means is disposed adjacent to the rotor, the means generally comprising a magnet which is so constructed that the N and S poles thereof alternately approach the rotor. The rotor follows the rotation of the rotor driving means to rotate in and stir the water sample.

Abstract: This invention relates to a reflector type screen suitable for use in a daylight room and which provides high luminance and a wide range of diffusion, wherein a specular surface is provided by an aluminum coating formed by vacuum evaporation on one side of a base plate of a transparent thermoplastic resin, and said specular surface is lined with a thin sheet of a flexible synthetic resin such as polyvinyl chloride thereby to protect the specular surface and to facilitate the subsequent processing. A transparent diffusing specular layer having a sandblast surface is formed on the other side of the base plate, and then lenticulars having a convex surface are formed in continuous rows by rolling with due caution not to damage the sandblast surface. The diffusing layer is prepared to have relatively low diffusing performance, e.g. 10 to 20%, thereby providing high luminance for viewers and a wide range of diffusion in the transverse direction.