SOME KEY PEOPLE IN BAROMETER DEVELOPMENT

EVANGELISTA TORRICELLI (1608 - 1647)

 In 1643 Evangelista Torricelli conducted an experiment. (Note- although he devised the experiment & predicted the results, it is probable that it was actually carried out by someone else). 

 Earlier Galileo had noticed that there was a limit to the height (aprox. 33' or 10m)  that water could be raised with a suction pump & Torricelli decided to find out why this was. By considering the results of previous experiments by others,it is likely that he reasoned that air had weight, and if it would support a  32' column of water, then it should also support about 30" of mercury. So using mercury, he filled a 4' - 1.2m long tube that was sealed at one end, put his finger over the open end and inverted it into a dish containing more mercury. On removing his finger the mercury flowed down the tube and stabilized at around 29" -737mm from the surface of that in the dish . Further experimentation established that the height of the column was dependent on the air pressure at the time. This became known as the Torricellian experiment. This apparatus was developed into the barometer, and was used for finding differences in height. 

ROBERT BOYLE (1627 - 1691)

Robert Boyle brought the idea of the barometer to England & improved on it by introducing a graduated scale so that variations in the height of the column could be directly read. He was also the first person to use the word "barometer" 

 Boyle went on to conduct many experiments concerning gases & vacuum, it was he that formulated the relationships of temperature, volume & pressure in gases (Boyles law).

ROBERT HOOK (1635 - 1723)

In the mid 1660's Robert hook devised a method of converting the linear movement of the mercury into a radial movement, so that a circular dial could be used. This had the effect of magnifying small variations in the height of the column and (in theory) could detect a 1/100" variation, thus inventing the wheel barometer.

LUCIEN VIDIE (1805 - 1866)