Question

Why is water not taken in torriceiley barometer in place of Mercury?

Answer 1

Mercury is relatively denser than water, consequently the length of the column of water would have to be about 34 feet high to exert pressure equal to that of the atmosphere while the column of mercury need to be  only30 inches to exert pressure equal to that of the atmosphere.

Answer 2

water could not easily observe because it is transparent
it sticks in the vessel so it will not give accurate reading