An improved reflecting system for use with tubular spirit levels

摘要

212,823. Tallack, H. T. Aug. 9, 1923. Levels.-Means for simultaneously observing both ends of the bubble of a spirit level comprise a plane mirror D disposed at an angle of 45‹ over one end of the bubble C and extending over the whole width of the tube B, and a doubly-reflecting prism E over the other end of the bubble, extending from one side of the tube to the centre. The reflectors are mounted in a box A secured to collars F on the tube. Specification 17944/10 is referred to.