Amanometer consists of an inclined glass tube which communicates with a metal cylinder standing upright; liquid fills the apparatus to a fixed zero mark on the tube when both the cylinder and the tube are open to atmosphere. the upper end of the cylinder is then connected to a gas supply at a pressure p and manometer liquid rises through a distance l in the tube. establish the relation;
h=sl [ sin(alpha) + (d/d)^2 ]

for the pressure head h of water column in terms of inclination alpha of the tube, specific gravity s of the fluid, and ratio of diameter d of the to the diameter d of the cylinder.

also determine the value of so that the error disregarding the change in level in the cylinder will not exceed 0.1 percent when = .