#barometers

It's really about how to balance the general history of barometers - their role in society, but also involve the object in question.. maybe it would be best to involve the general history through the use of Merryweather's barometer? To have it as an entry point to the subject? Does that make sense?

-- most common unit of pressure is the atmosphere

-- an atmosphere is the average pressure at sea level

-- atmosphere is abbreviated atm

-- the SI unit of pressure is pascal

-- pascal is abbreviated pa

-- 1 Pa = 1 N/m^2

-- 1 atm = 101,325 Pa

-- millimeter of mercury comes from how pressure is measured with a barometer

-- millimeter of mercury is abbreviated mmHg

-- millimeter of mercury is also called a torr

-- 1 atm = 760 mmHg

-- 1 mmHg = 1 torr

-- inches of mercury is abbreviated in.Hg

-- pounds per square inch is abbreviated psi

-- 1 atm = 29.92 in. Hg

-- 1 atm = 14.7 psi

The Tempest Prognosticator, AKA The Leech Barometer

Invented around 1850 by an English physician named George Merryweather, the Tempest Prognosticator was a device created for the purpose of predicting oncoming storms.  What made the Tempest Prognosticator especially unusual was that it used live leeches, medical leeches in fact, which came from Dr. Merrweather's own supply.  The Tempest Prognosticator featured 12 small bottles filled with water, each of which contained a live leech.  The idea was that when a storm was coming, the leeches would be disturbed by the change in pressure or electromagnetic changes in the atmosphere.  They would then climb to the top of the bottles attempting to enter a small metal tube, setting off a trigger which rang a bell at the top of the device. If several bells went off in quick succession then it can be assured a storm was on its way.

Dr. Merryweather spent many years promoting his device, claiming that it was highly accurate. He even lobbied the British Government to adopt the device and set up stations along the British coast.  Unfortunately for Dr. Merryweather, the Tempest Prognosticator never caught on, especially due to the invention of modern barometers using mercury, alcohol, water, and other chemicals to detect atmospheric pressure changes. Such devices were more accurate, easier to use, and did not require the owner to raise and feed live leeches.

Michelangelo Ricci – Scientist of the Day

Michelangelo Ricci, a Roman mathematician and Church official, was born Jan. 30, 1619.  

Guillaume Amontons – Scientist of the Day

Guillaume Amontons, a French scientific instrument maker and inventor, was born Aug. 31, 1663.

Blaise Pascal – Scientist of the Day

Blaise Pascal, a French mathematician and physicist, was born June 19, 1623.