A double-column enlarged-ends manometer is used to measure a small pressure differ- ence between the two points of a system conveying air under pressure, the diameter of U-tube being 1/10 of the diameter of the enlarged ends. The heavy liquid used is water and the lighter liquid in both limbs is oil of relative density 0.82. Assuming the surfaces of the lighter liquid to remain in the enlarged ends, determine the difference in pressure in millimetres of water for a manometer displacement of 50 mm. What would be the manometer reading if carbon tetrachloride (of relative density 1.6) were used in place of water, the pressure conditions remaining the same?