The revised theory of thermal transpiration by Wu has been applied to the case of a modified Absolute Manometer for any temperature ratios and arbitrary accommodation coefficients on the boundaries of the three plates. According to the Lockenvitz’s approximate theory the pressure on the central vane is independent of its temperature. This paper explicitly shows that the pressure on the central vane is dependent on its temperature. A comparison of both theories has been discussed extensively for arbitrary temperature on the central plate.