Improvements in or relating to sight gauges

1,127,811. Liquid level indication. ROLLS ROYCE Ltd. Feb. 6, 1967 [Feb. 10, 1966], No. 5793/66. Heading G1H. In a sight a triangular bore 12, in a transparent plastic block 10, in which the height of a liquid is to be indicated has surfaces 30, 32 so disposed that when viewed on the direction A light will pass directly from the liquid filled portion of bore 10 in a direction perpendicular to the viewing surface 20 but in the empty portion of bore 12 total internal reflection occurs and light passing towards the surfaces 30, 32 in a direction perpendicular to the surfaces is reflected off such surfaces. Marked plates 26, 28 34, reflect letters, numerals, signs or symbols on to surfaces 30, 32 of the portion of the bore 12 not containing liquid. Different shaped bores 12 are disclosed.