Who devised for the first time,a method for measuring atmospheric pressure?

At what speed,the velocity head of water is equal to the pressure head of $40 \, cm$ of mercury? (Given: Density of mercury = $13.6 \times 10^3 \, kg/m^3$,Density of water = $10^3 \, kg/m^3$,$g = 9.8 \, m/s^2$)

An inverted tube barometer is kept on a lift moving downward with a deceleration $\alpha$. The density of mercury is $\rho$ and the acceleration due to gravity is $g$. If the atmospheric pressure is $P_0$,then:

Torricelli's barometer used mercury. Pascal duplicated it using French wine of density $984 \; kg \; m^{-3}$. Determine the height (in $m$) of the wine column for normal atmospheric pressure.

The pressure at half the depth of a lake is $2/3$ of the pressure at its bottom. What is the depth of the lake in $m$?

$A$ barometer is kept in an elevator accelerating upwards with an acceleration $a$. Find the most likely pressure inside the elevator.