Sympiesometer
Encyclopedia
A sympiesometer is a compact and lightweight type of barometer
that was widely used on ships in the 19th century.
The sympiesometer consists of two parts. One is a traditional mercury thermometer that is needed to calculate the expansion or contraction of the fluid in the barometer proper. The other is the barometer, consisting of a J-shaped tube open at the lower end and closed at the top, with small reservoirs at both ends of the tube. The lower end of the J and its associated reservoir were filled with colored almond oil, while the upper portion and its reservoir were filled with hydrogen
gas. Increasing air pressure would cause the oil to be pushed out of the lower reservoir and into the tube, compressing the hydrogen gas into the upper reservoir. The pressure was indicated by the position of the top of the oil. To correct for temperature, a sliding scale was used; the operator would first use the thermometer to set the scale and then measure the pressure from it.
The basic idea is similar to the common weather glass
that had been in use for some time, but the use of highly compressible hydrogen in a long, thin tube allowed much more accurate measurements, as changes in pressure resulted in much more movement of the liquid. The basic concept was initially demonstrated by Robert Hooke
, which he referred to as the Otheometer. However it remained unused until it was re-introduced by Alexander Adie
.
Barometer
A barometer is a scientific instrument used in meteorology to measure atmospheric pressure. Pressure tendency can forecast short term changes in the weather...
that was widely used on ships in the 19th century.
The sympiesometer consists of two parts. One is a traditional mercury thermometer that is needed to calculate the expansion or contraction of the fluid in the barometer proper. The other is the barometer, consisting of a J-shaped tube open at the lower end and closed at the top, with small reservoirs at both ends of the tube. The lower end of the J and its associated reservoir were filled with colored almond oil, while the upper portion and its reservoir were filled with hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
gas. Increasing air pressure would cause the oil to be pushed out of the lower reservoir and into the tube, compressing the hydrogen gas into the upper reservoir. The pressure was indicated by the position of the top of the oil. To correct for temperature, a sliding scale was used; the operator would first use the thermometer to set the scale and then measure the pressure from it.
The basic idea is similar to the common weather glass
Barometer
A barometer is a scientific instrument used in meteorology to measure atmospheric pressure. Pressure tendency can forecast short term changes in the weather...
that had been in use for some time, but the use of highly compressible hydrogen in a long, thin tube allowed much more accurate measurements, as changes in pressure resulted in much more movement of the liquid. The basic concept was initially demonstrated by Robert Hooke
Robert Hooke
Robert Hooke FRS was an English natural philosopher, architect and polymath.His adult life comprised three distinct periods: as a scientific inquirer lacking money; achieving great wealth and standing through his reputation for hard work and scrupulous honesty following the great fire of 1666, but...
, which he referred to as the Otheometer. However it remained unused until it was re-introduced by Alexander Adie
Alexander Adie
Alexander James Adie FRSE was a Scottish maker of medical instruments, optician and meteorologist. He was the inventor of the sympiesometer, patented in 1818....
.