While the exact inventor of the mercury manometer is difficult to pinpoint, Evangelista Torricelli is widely credited with its development in the 17th century.

Here's why:

* Torricelli's Experiment: Torricelli famously conducted an experiment in 1643 where he filled a glass tube with mercury and inverted it into a dish of mercury. This created a vacuum at the top of the tube and demonstrated that air pressure could support a column of mercury. This experiment is considered the foundation of the barometer, which is a type of manometer.

* Early Manometers: While Torricelli didn't explicitly create a manometer as we know it today, his work laid the groundwork for the development of pressure-measuring devices.

* Later Adaptations: Other scientists and engineers built upon Torricelli's ideas, adapting and refining the design of pressure measuring devices.

Therefore, while not the sole inventor, Torricelli's crucial contributions to understanding atmospheric pressure and his experiment with mercury are considered fundamental to the development of the mercury manometer.