How High is Blue? (1851)

JF Ptak Science Books   Quick Post

What struck me in this technical illustration is the cross-section of the ocean of air, and the attempt to depict the characteristics of the atmosphere in receding qualities of blueness. This seems a natural thing to attempt, but I can’t really remember seeing anything quite like this from the mid-19th century–sure there there are images showing the height of the atmosphere, but I just can’t recall the point being made in shades of blue. The image itself is a large detail from “Illustrations of Natural Philosophy, Pneumatics”, a colored lithograph by John Philipps Emslie, and made in 1851.  This copy is from the Wellcome Collection, London, and try as I might I have not yet been able to find out in what book (if any) in which this work was published. Emslie was very active, and composed a number of complicated technical and data visualization efforts like this one, but I can’t yet find publication details.  In the meantime, I’m posting this, concentrating on the atmosphere.

So far as the heights go in this image, we get through the troposphere and stratosphere, and most of the way through the mesosphere, and so far as the oxygen content goes at the various altitudes, the faded blueness for the relative ease of breathing air is fairly not-so-correct, but that’s not what the intention of the graphic was supposed to show…I was just trying to match-up the blueness with something besides height. The practical experience of humans in 1851 was extremely limited, the record ascension in a balloon at this point still stood at about 27,000′ and was made in 1837–the next big step would be in 1862 when the record was set at 39,000′, which was about 10,000′ higher than any mountain on Earth, the flight subjecting the aeronauts to the thrills of extremely low air pressure and cold. Anyway, the print does get its point across. 

Emslie pneumatics detail

Source: the Wellcome Collection, http://j.mp/2zAatJn

The full image: 

Emslie pneumatics

By: JF Ptak Science Books
Via: Feedbin Starred Entries
Source: http://j.mp/2zn3cvw

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