Tag Archives: joseph banks

Biography, Chemistry, History, History of Science

Humphry Davy – Finding Love in the Colourful Age of Romantic Science

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You’re a young 33, with an already impressive scientific career under your belt, and – although you only suspect it – a spectacular future ahead of you. Within 10 years, you’ll be elected President of the Royal Society.

But in November 1811, you’ve got something else on your mind.

How exactly would Humphry Davy (he of Davy Lamp fame among many other achievements) impress the first true love of his life – the beautiful widow and heiress Jane Apreece ?

Well, as it turned out……with more science of course.  And unlikely as it might seem, with quotes from the book whose spine forms the header of this very blog: Erasmus Darwin’s Zoonomia. (Erasmus was Charles Darwin’s grandfather….how many times)

Over to you, Humph….

‘There is a law of sensation which may be called the law of continuity & contrast of which you may read in Darwin’s Zoonomia [sic].  An example is – look long on a spot of pink, & close your eyes, the impression will continue for some time & will then be succeeded by a green light.  For some days after I quitted you I had the pink light in my eyes & the rosy feelings in my heart, but now the green hue & feelings – not of jealousy – but of regret are come.’

Smooth, or what?

I’m not the first to spot Davy’s creative application of ground-breaking ideas in colour perception; the above passage is from Richard Holmes’s award-winning Age of Wonder.  But what’s it all about?   Let’s start with Zoonomia.

Erasmus describes his experiments on colour and the eye in Volume I, Section III: Motions of the Retina; and Section XI: Ocular Spectra.

In his letter to Jane Apreece, Davy is referring to this experiment (Warning for the unfamiliar: f = s):

Zoonomia Vol1 Section III, p.20

Later, Erasmus restates the experiment and proposes a mechanism for the observed effect:

Zoonomia Vol1 Section III
Red Spot (Zoonomia V1 S.III p.14)

Darwin’s experiments covered a range of colour and contrast effects.  Here in his ‘tadpole’ experiment he interprets the bright after-image  we see after staring at a dark object, explained again in terms of conditioning and sensitivity of the retina.


Erasmus’s ‘tadpole’ (a little smudged after 200 years)

The drawings in Zoonomia are individually hand drawn and hand coloured.  In this passage, Erasmus encourages his readers to partake of some drawing-room diversion using silks of many colours:

Erasmus encourages his readers to lay down silks
Readers are encourgaged to lay down coloured silks

All exciting stuff, not least for Erasmus, who betrays his giddiness in this chuckling wind up to his analysis, where he curries favour with the incumbent president of the Royal Society, Sir Joseph Banks.

Joseph Banks“I was surprised, and agreeably amused, with the following experiment.  I covered a paper about four inches square with yellow, and with a pen filled with a blue colour wrote upon the middle of it the word BANKS in capitals, and sitting with my back to the sun, fixed my eyes for a minute exactly on the centre of the letter N in the middle of the word;after closing my eyes, and shading them somewhat with my hand, the word was dinstinctly seen in the spectrum in yellow letters on a blue field; and then, on opening my eyes on a yellowish wall at twenty feet distance, the magnified name of BANKS appeared written on the wall in golden characters.” [Banks was elected President of the Royal Society in 1778].

Erasmus saw Banks’s name in large golden letters on his garden wall

Did Erasmus get it right with all that stuff about flexing of the antagonist fibres and analogy to the muscles? Well, he wasn’t a million miles away from the truth.   Indeed, it looks like yet another case of Erasmus Darwin not getting the credit he deserves for being ahead of the game.

Here’s a modern popular version of the tadpole ‘trick’ (Credit: from here)

The idea is you stare at the bulb for 20 or 30 seconds then look at the white space to the right of it.  The popular description of the effect is in terms of  the retina cells stimulated by the light portions of the image being desensitized more than those which respond to the dark part of the image – so that the least depleted cells react more strongly when the eye switches to the more uniform all-white image next to the bulb.

Davy Lamp (Wiki Commons)

The modern authors note also that the size of the afterimage varies directly with the distance of the surface on which it is viewed: a manifestation of Emmert’s Law.  This is consistent with Erasmus’s report of the name BANKS writ large on his garden wall.

Likewise, the modern interpretation of colour afterimages is popularly framed in terms of how ‘fatigued’ cells respond to light (See how fatigued’ aligns with Erasmus’s muscular references).  Erasmus didn’t know we have two types of light-sensitive cells in the eye: cones (that broadly speaking detect colour) and rods (that are more sensitive to absolute brightness), and that the cones themselves are sub-divided to be maximally sensitive to red , blue and green (RGB).

But he did understand the concept of complementary colours, and recognised that whatever part of the retina detects the colour red becomes fatigued through over-exposure; he’d got the principle that green appears againt white as a kind of negative red ).

If we dig a little deeper we find the brain-proper conspires with the retina to consider what we see in terms of black-white, red-green, and blue-yellow opponencies.  And the corresponding three sets of retinal cells operate in a pretty arithmetical fashion: the electrical impulse sent to the brain by the red-green cells is proportional to the net red-green exposure to light that the cell has experienced in recent time; likewise the blue-yellow sensitive cells.

That’s all clear then.

What bugs me a wee bit is that in my research for this post I never once saw a reference to Erasmus Darwin.  Rather, the standard historical reference seems to be the German psychologist Ewald Hering (1834-1919), who is credited with the first observations of the phenomenon.

Hold the horses – it’s Valentines Day

Ok, we got a bit lost in the science there.  And I got a bit hot under the collar; eh-hem.   So, the real question is: did Davy’s colourful overtures hit the mark?  Well, sort of.  Humphry Davy and Jane Apreece married the following year in 1812.  The bad news is it didn’t really work out longterm.

All the same, Davy shone ever bright in his science.  Already famous for discovering a whole range of new chemical elements, including via separation by electrolysis potassium and sodium, and chlorine gas; he went on to discover elemental iodine and, for good measure, invented the Davy Lamp – thereby saving who knows how many thousands of lives in the mining indistry.   In 1820, when Banks’s death ended his 40+ year run at the head of the Royal Society, Davy was elected President.

All of which doubtless kept a bit of colour in his cheeks.

Shop-front in Penzance where Davy served his early apprenticeship (Tks S.Klinge)

Sources

Darwin, Erasmus. Zoonomia Vol 1 Pub. J.Johnson 1796 (photos are from author’s copy)

Holmes, Richard. Age of Wonder. Pub. Harper Press (the softback is out for about £7 now – buy it!)

And Resources

The Guttenburg version of Zoonomia Vol 1 is here.

 


Art, Biography, Books, History, sciart

Royal Institution Speaker Calls for an End To Culture Wars

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Yesterday evening at the Royal Institution, I watched the respected biographer and academic Richard Holmes make an empassioned plea for an end to the ‘two cultures’ rift between science and the arts – a reference  to the term coined by CP Snow in his Rede Lecture of 1959.

Coleridge with his biographer, Richard Holmes, at the RI last night. Photo Sven Klinge
Coleridge with his biographer, Richard Holmes, at the RI last night. (Photo Sven Klinge)

In a packed auditorium, familiar as the venue for the annual Christmas Lectures, Holmes challenged his hosts to do their bit by including humanities speakers as a fixture in the RI lecture programme.   He certainly held the historical high ground, sharing a daiz occupied in another age by Sir Humphrey Davey, Michael Faraday and significantly the poet Samuel Coleridge.

Faraday at the Royal Institution
Faraday at the Royal Institution

Dipping into his new book The Age of Wonder, Holmes used the lives and achievements of explorers like Sir Joseph Banks and the romantic polymath Erasmus Darwin (grandfather to Charles) to illustrate an age when science and art moved together to their mutual benefit.  He continued through the lives of the Herschels: from William and Catherine and the discovery of Uranus, to Catherine’s formative influence on the young John Herschel.  Then on to Humphrey Davy and Michael Faraday, finishing with Charles Darwin in the mid-nineteenth century.   Readers who enjoyed hearing about Joseph Banks’s culturally sensitive integration activities in this earlier post on the Otaheite Dog, will find more revelations in the same vein in Age of Wonder.

Samuel Taylor Coleridge
Samuel Taylor Coleridge

Holmes  bemoaned the lack of general access to source texts, including Banks’s Endeavour Journal and Darwin’s Botanic Garden – another sign of the literary/science imbalance of two cultures thinking.  Both of these works are wonderful pieces of literature as well as scientific documents.   The Botanic garden is a compendium of virtually all 18th century science expressed as poetry, in a format where the footnotes are as inspiring as the main text.    The good news is that both are available online.

Richard Holmes (Photo courtesy Sven Klinge)
Richard Holmes (Photo courtesy Sven Klinge)
Age of Wonder
Age of Wonder

Holmes believes that if there there was one event more than any other that influenced Snow’s proclamation on the two cultures, it was the horrific association of science with the atomic bomb.   An audience member blamed the divide in the UK on the arts/science choices students were forced to make at A-Level.   Whatever the reason, Holmes’s comments are a timely introduction to a week in which the two cultures theme figures large, with as part of the London Consortium’s Art and Science Now Programme,  a mix of all-day conference sessions and receptions  scheduled at the Wellcome Institute on Thursday, the Science Museums’s Dana Centre on Friday, and the  Tate Modern Art Gallery on  Saturday.  More on those later.

UPDATE:  My report on the Art and Science Now ‘Two Cultures’ event is HERE

animals, evolution, History

Roast Dog and Aquatint

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In 1769, James Cook visited the island of Otaheite, or modern Tahiti, to observe the transit of venus.

And these are the Otaheite Dog and Wolf, or at least 1788 aquatint renditions of them, made with some license if the awkward stance and anthropomorphic gaze are to be believed;  but let that not distract from their story.

Acquatint of the Otaheite Dog by Charles Catton (Tim Jones's collection)
Acquatint of the Otaheite Wolf by Charles Catton (Tim Jones's collection)

Drawn from life, engraved, and published by Charles Catton in his ‘Animals, Drawn From Nature and Engraved in Aqua-tinta‘, in 1788, the prints are technically interesting as representing the first use of aquatint for natural history illustration.

Catton started life as a coach painter, expertly representing animals in heraldry, and achieving the rank of coach painter to George III. Later in his career he helped document animals observed by adventurers like John White, who travelled to the South Seas in 1787, and whose ‘A Journal of a Voyage to New South Wales’ featured Catton’s picture of an Australian kangeroo.  Like most artists at this time,  Catton didn’t actually travel with the explorers, but worked from live and dead specimens sent home from the New World expeditions.

Catton's Kangeroo for John White

A contemporary advertisement for the journal contains a statement on accuracy that, applied to the Otaheite dog, is indefensibile by modern standards:

“The Public may rely, with the most perfect confidence, on the care and accuracy with which the drawings have been copied from nature, by Miss Stone, Mr. Catton, Mr. Nodder, and other artists; and the Editor flatters himself the Engravings are all executed with equal correctness, by, or under the immediate inspection of Mr. Milton.”

Despite their failings, Catton’s aquatints were an honest attempt to represent reality.  What they lack, with the animals drawn dead and out of context, is any essence of the beasts: be that energy, poise, or sloth.

Catton’s Otaheite dog and wolf look similar, which is intriguing given John White made the same observation of their Australian counterparts:

“This animal is a variety of the dog, and, like the shepherd’s dog in most countries, approaches near to the original of the species, which is the wolf, but is not so large, and does not stand so high on its legs.

The ears are short, and erect, the tail rather bushy; the hair, which is of a reddish-dun colour, is long and thick, but strait. It is capable of barking, although not so readily as the European dogs; is very ill-natured and vicious, and snarls, howls, and moans, like dogs in common.

Whether this is the only dog in New South Wales, and whether they have it in a wild state, is not mentioned; but I should be inclined to believe they had no other; in which case it will constitute the wolf of that country; and that which is domesticated is only the wild dog tamed, without having yet produced a variety, as in some parts of America.”

Note the language: “approaches near to the original of the species”.  Some concept of evolution clearly existed way before Darwin published his 1859 Origin of Species.

Joseph Banks
Joseph Banks

The London Natural History Museum’s beautiful ‘Voyages of Discovery’ describes the Pacific crossing made by James Cook, Sir Joseph Banks, and Sydney Parkinson on the Endeavour, including their visit to Otaheite. What it fails to mention is the Otaheite dog and, more importantly – how to cook it.  For that we must turn to primary sources.  In ‘A Journey of a Voyage to the South Seas‘, Sydney Parkinson describes how civilised Englishmen came to share the Otaheite locals’ penchant for tasty roast dog:

fire“These people also are fond of dog’s-flesh, and reckon it delicious food, which we discovered by their bringing the leg of a dog roasted to sell. Mr. Banks ate a piece of it, and admired it much. He went out immediately and bought one, and gave it to some Indians to kill and dress it in their manner, which they did accordingly. After having held the dog’s mouth down to the pit of his stomach till he was stifled, they made a parcel of stones hot upon the ground, laid him upon them, and singed off the hair, then scraped his skin with a cocoa shell, and rubbed it with coral; after which they took out the entrails, laid them all carefully on the stones, and after they were broiled ate them with great goût; nor did some of our people scruple to partake with them of this indelicate repast. Hav-ing scraped and washed the dog’s body clean, they prepared an oven of hot stones, covered them with bread-fruit leaves, and laid it upon them, with liver, heart and lungs, pouring a cocoa-nut full of blood upon them, covering them too with more leaves and hot stones, and inclosed the whole with earth patted down very close to keep in the heat. It was about four hours in the oven, and at night it was served up for supper: I ate a little of it; it had the taste of coarse beef, and a strong disagreeable smell; but Captain Cook, Mr. Banks, and Dr. Solander, commended it highly, saying it was the sweetest meat they had ever tasted; but the rest of our people could not be prevailed on to ate any of it.”

And that about wraps it up for the Otaheite Dog.  Yummy.