Monday, 16 March 2015

Blueprint

Anna Children was born on 16th March 1799 and she was tribbed with today's Google-doodle. I need to have this information thrust under my nose because I've never heard of this pioneering botanist and photographer and I think we should.  She was there at the beginning and she moved in privileged circles - her father was a scientific polymath/dabbler who was at one time Secretary to the Royal Society but Anna was born 100 years too early to be dubbed FRS herself. The father John George Children should be given more credit because, after a home-lab conflagration >!whooomph!< he recommended the use of safety-goggles. Anna was a family friend of William Henry Fox Talbot and Sir William Herschel, whom we've met before discovering planets with his sister Caroline.  Talbot and his oppo Louis Daguerre in France were independently developing the technology and techniques (different!) of photography in the late 1830s standing on the shoulders of chemists of the previous generation.  Their discoveries and tastes dictated the way in which photography became available.  It could have gone in different directions using different chemical reactions but it worked and that put a damper on blue-skies research to discover other Ways of Seeing.  William Herschel invented a totally novel chemical technique for recording fine detail.  He required the process as an early form of backup, so that his notes and diagrams could be recorded indelibly. The chemistry involves mixing 8% potassium ferricyanide and 20% ferric ammonium citrate and slapping it on an absorbent material - usually paper or cloth.  On exposure to light the iron is reduced to form a complex called Iron(II,III) hexacyanoferrate(II,III) aka ferric ferrocyanide aka Prussian Blue, an insoluble blue dye.
The advantages of this cheap and cheerful process were immediately recognised by technologists, engineers and architects and gave us the word blueprint - as a fundamental and accurately reproduced template.  It exercised the adopters of the alternative silver-based process in ways out of all proportion to the issue at hand.  Why not have a landscape with a blue tinge?  Why did the monochrome have to be black? Very interesting essay on the photographic angle.

Anna had by now married a well-heeled merchant called John Atkins and was developing a passion for botany in particular for the architectural divergences within the Algae.  She found that she couldn't easily record sufficient detail time-efficiently and used Herschel's cyanotype process to accumulate a huge archive of images. These were published in a severely limited edition, which has now acquired significant value for its rarity . . . as well as for its record of the diversity of botanic life.  There is a dilemma here: I was taught that you had to draw specimens because the details were only visible to the trained human eye.  Effectively this meant that we drew but we also interpreted the specimen and to do that we had to have a hypothesis about what we were seeing. Looking at the cells of an onion skin, we knew there were nuclei so we drew nuclei and duly labelled them as such from the margin of the drawing.  The problem was that we also knew there were mitochondria in the cells and so we would be tempted to draw them too . . . although at 1μm they were beyond the resolution of the optical microscopes that we were using. Drawing thus tilts the object so it shines a little brighter than it really is - to the detriment of object truth.  This is one of the reasons why I welcome the smart-phone into my introductory biology labs - it gives an extra 4x magnification but it also is accurate.  I also regret the arrival of this technology because it can be used to bypass the brain altogether.

Anna Atkins wasn't having any of that - she wanted an accurate record, she wanted it fast and she didn't give a tuppenny damn if it was blue. Brilliant!

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