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Welcome to Trailblazing

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Welcome to Trailblazing, an interactive timeline for everybody with an interest in science. Compiled by scientists, science communicators and historians – and co-ordinated by Professor Michael Thompson FRS – it celebrates three and a half centuries of scientific endeavour and has been launched to commemorate the Royal Society’s 350th anniversary in 2010.

Trailblazing is a user-friendly, ‘explore-at-your-own-pace’, virtual journey through science. It showcases sixty fascinating and inspiring articles selected from an archive of more than 60,000 published by the Royal Society between 1665 and 2010.

Use the slider or the Forward/back 50 years arrows to move around the timeline. Best viewed at screen resolution of 1280x1024 resolution or higher.

Scientific articles are displayed as red circles. Rollover the circle for a summary and click the tabs for more information. There is a short introduction and also links to full scientific articles. You can print the information too.

Historic events are shown by silver circles. Rolling the mouse over the silver circle will summarise the event.

Highlight commentaries in will filter the timeline, to show you only the scientific articles that relate to that topic.

You can also download highlighted commentaries as PDF.

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1826

How the Earth’s atmosphere changes with height

John Dalton wrote about a subject of tremendous importance for the global environment: the chemical composition of the atmosphere. He began by stating some familiar laws, and then described a laboratory experiment in which two gases were mixed. Dalton recognized an important limitation of his laboratory experiment. His laboratory was small in size, but the atmosphere is much larger; thus, air pressure would vary between that at the Earth's surface and that further up in the atmosphere. Dalton then drew on another important ‘science tool’, the thought experiment, and thus arrived at his conclusions. Science is an ongoing process: a chain of experiments and reasoning. So, just as the laboratory experiment was limited, and required a new way of thinking, Dalton immediately recognized the limitations of that too: ‘All that we have said hitherto has been relating to “quiescent” atmospheres ... How the case would be with regard to the earth’s atmosphere, such as it actually is, ... is not very easy to ascertain …’ And, indeed, there was still much to learn; we return to this important topic over a century later in the 1946 timeline entry on the Brewer–Dobson circulation.

Bjoern Hassler, University of Cambridge.

This commentary is free to share under a Creative Commons license

1. More on John Dalton

2. Atmospheric composition and structure

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Dalton`s table of elements

John Dalton's table of symbols representing elements and compounds. From A New System of Chemical Philosophy, 1808.

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