"When two Englishmen meet their first talk is of the weather" - Samuel Johnson
Discussing the weather was far from a simple ice-breaker in 17th century Britain. Agriculture and trade were affected by severe events of the period, most memorably commemorated in scenes such as the London Frost Fair on the frozen Thames river in 1683-84. In response, men of science developed meteorological instruments and applied them to gain a more systematic understanding of weather and climate. This exhibit will guide you through the main theories and inventions of the 17th and 18th century which laid the foundations of weather science.
Meteorological instruments
The science of the weather is founded on observation and the recording of data elements such as temperature, humidity and air pressure. Following the Baconian method, various instruments were developed to measure changes in the weather and improve understanding of the atmosphere.
"Frog" thermometer (1657/1667) by Ferdinand II de' Medici [attr.]Museo Galileo - Istituto e Museo di Storia della Scienza
The development of meteorological instruments in 17th century Britain continued the work of the Accademia del Cimento of Florence. The Accademia had, for instance, developed Galilean thermometers - pictured here - to capture changes in temperature.
Discover how they were made in this video of the Museo Galileo.
Thermometers (1688) by Joachim d'Alence (after)The Royal Society
Early thermometers, such as these decorative French instruments, would employ alcohol and water, making them largely unreliable. Dutch instrument-maker Daniel Gabriel Fahrenheit FRS (1686-1736) invented a thermometer with a precise and standardised scale to be read against a mercury column.
Barometer (1669) by Robert Boyle (1627-1691)The Royal Society
Relying on the expertise of instrument-makers of London, Fellows of the Royal Society devised various ingenious devices to capture the variations in temperature, humidity, wind or air pressure such as this barometer invented by Robert Boyle FRS (1627-1691) and Robert Hooke (1635-1703) the Society's first Curator of Experiments.
Weather clock (1663-12-09) by Christopher Wren (1632-1723)The Royal Society
Sir Christopher Wren FRS (1632-1723) designed various meteorological instruments including a rain-gauge that emptied itself and this Weather Clock. The clock was intended to automate the business of recording pressure changes and wind. A vane at the top-right captured wind directions while time and barometric observations were recorded to the left of the clock, with pen and paper scroll.
Instruments necessary to make a diary of the weather (1744) by Roger PickeringThe Royal Society
By the 18th century, reliable instruments were being proposed as a means of capturing standard forms of data on the weather across many sites.
Hygrometers as in Fig. 6 recorded humidity by stringing natural materials such as a hair, or in this case an oat-beard. As the oat swells when moist, the dial at the top indicates - crudely - the level of humidity in the air.
The author suggested hanging the hygrometer under shelter to protect it from precipitations. A sponge has been added to the set-up in Fig. 1, as another means of judging how much water is in the air.
A rain gauge (named an ‘ombrometer’ by the author) collects precipitation in a quantified column in Fig. 5 (and detail).
In Fig. 6, the weather vane indicates both wind speed and direction.
Scientific bases of meteorology
The boom in instruments in the 17th century underpinned a program of experiments which in turn enabled scientists to formulate some of the fundamental laws that govern the natural world.
PV = k
Robert Boyle FRS (1627-1691) determined the relationship between gaseous volume, pressure and temperature. Boyle’s Law, as it is now known, was critical to founding a science of the weather. Simply stated, this ideal gas law describes how the volume of a gas (V) increases as pressure (P) decreases, at a constant temperature (k). It was a crucial step to understand how barometric readings worked.
List of experiments to be made in the air-pump (1660) by Robert Boyle (1627-1691)The Royal Society
Boyle's primary interest was to determine the nature of the air. A chemist and alchemist, he wanted to observe the transformation of elements under various conditions, as described in this wish-list of experiments with his new air-pump.
Barometer (1669) by Robert Boyle (1627-1691)The Royal Society
Boyle was one of the earliest to use barometers in the British Isles. The instrument had first been developed by one of Galileo's student, Evangelista Torricelli (1608-1647) and Boyle and Hooke further adapted the instrument shown on this illustration.
In his Experimental History of Cold, Boyle described various experiments he and Robert Hooke conducted to look at the effect of low temperatures.
Trade winds
Building on Boyle's experiments, the astronomer and polymath Edmond Halley FRS (1656-1742) wrote on problems of barometric pressure. By connecting Boyle's experiments to the latest theories on air pressure and his own observations in the Atlantic, he explained the behaviour of mercury during storms and at the equator. He also created the first weather map showing worldwide prevailing winds at sea.
A discourse of the rule of the decrease of the height of the mercury in the barometer (1686-05-25) by Edmond Halley (1656-1742)The Royal Society
Edmé Mariotte (1620-1684) of the Académie des Sciences had independently confirmed Boyle's law, proving additionally that temperature affects pressure.
In turn, Halley considered the effect of altitude on barometric pressure, and how this might be interpreted in weather observations.
Map of the trade winds (1686) by Edmond Halley (1656-1742)The Royal Society
In 1686, Halley published this landmark chart, recording worldwide wind conditions that still prevail today. For example, you can see predominantly easterly winds circling the Earth at the Equator.
Halley had travelled to the Atlantic island of St Helena to observe the transit of Venus in 1676. He also gathered the observations of various sailors to realise the chart.
He also mapped the trajectory of the Indian monsoon.
Halley was the first to use dashes with arrows to point to the direction of winds.
The winds he described were crucial for navigation. They were termed ‘trade winds’ because commercial sailing vessels relied upon them to ply routes between Africa, Europe and the Americas.
Watch this video to discover more about Halley and his sea voyage.
F = ma
Sir Isaac Newton FRS (1643-1727) formulated fundamental laws of physics which explained how atmospheric forces work. In particular his second law dictated that an acceleration (a) results from a specific force (F) being applied.
Philosophiae Naturalis Principia Mathematica, by Isaac Newton (1685) by Isaac Newton (1643-1727)The Royal Society
In his most important published work, Principia Mathematica, Newton formulated three laws of motion. Considered to be the foundation of mechanics, the laws of motion became the tool which allowed scientists to express atmospheric forces in mathematical terms.
Watch the video to discover more on Principia Mathematica.
The 17th century marked the beginning of meteorology as a science. You can discover in our other stories how, in the 19th century, advances in physics, chemistry, instrumentation and statistics coallesced to form a modern science.
All rights reserved © The Royal Society 2020
The digital and physical exhibits were curated by Dr Catherine Ross (National Meteorological Archive, Met Office) and Dr Louisiane Ferlier (The Royal Society).
