John Dudley Profile picture
Dec 7, 2022 12 tweets 4 min read Read on X
Something different! Delighted to announce that a paper I wrote 22 years ago (!) on a supposed portrait of English scientist Thomas Harriot (c1560-1621) is finally online: TL;DR: Sorry but there's no real evidence that the portrait is Harriot ... 🧵 hal.archives-ouvertes.fr/hal-03839673
Image
Harriot was a polymath. He produced the first telescopic drawing of the moon before Galileo, he discovered the law of refraction before Snell or Descartes, and he explored Virginia, learning Algonquian to translate. It would be nice to know what he looked like. Image
It was @libroraptor who first got me interested in Harriot. And even 22 years ago, books and websites were often reproducing a portrait from the University of Oxford which was “claimed to be” Harriot. This wording intrigued me, so I started to look into it.
The portrait was bequeathed to Trinity College Oxford by James Ingram but there is no provenance before 1850 and no knowledge of painter or sitter. But the 20th century saw the portrait (left) linked to an engraving by Francis Delaram (right) of a man with a calculating board. Image
The rather odd story of the association between the Trinity College painting and the Delaram engraving (and the connection with Harriot) was explained in 1955 in Engraving in England in the 16th and 17th Centuries by Arthur M. Hind (1880-1957) Image
Robertson thought of Harriot because the calculating board suggests a mathematician and the verse suggests a friend of Chapman (Harriot was both). But it's tenuous. And the resemblance with the portrait is wishful thinking - bearded men with ruffs were very common at the time!
Harriot's age of 42 on the Oxford portrait did fit but whilst AN° DNI. 1602. ÆTATIS SVÆ 42 was correct at at the time Hind’s book, in 1957 the portrait was cleaned and it was discovered that the inscription had been modified. It was later X-rayed in 1964. Image
The results of all this were discussed between the President of Trinity College Arthur Norrington and the Director of the National Portrait Gallery David Piper. The "Harriot" age of 42 appears to have been a later overpainting and Piper states that this seems to rule out Harriot. Image
So unfortunately there appears to be no reason to associate the Oxford portrait with Harriot which is a shame because it would nice to have a face to put to a great scientist and explorer. Still when all this is taken together it's a nice story!
This was actually published in April 2000 in the Thomas Harriot Seminar Newsletter but since this is hard to find I have placed it online at HAL. Associating the portrait with Harriot is harmless enough, but it's important to understand it is not really supported by any evidence. Image
And I'd really like to thank @libroraptor again as well as @MatthewSteggle who was at Oxford 22 years ago and who helped dig things out from dusty places, and Clare Hopkins from Trinity College for the encouragement to get this story out there in 2022!
@libroraptor @MatthewSteggle @threadreaderapp unroll

• • •

Missing some Tweet in this thread? You can try to force a refresh
 

Keep Current with John Dudley

John Dudley Profile picture

Stay in touch and get notified when new unrolls are available from this author!

Read all threads

This Thread may be Removed Anytime!

PDF

Twitter may remove this content at anytime! Save it as PDF for later use!

Try unrolling a thread yourself!

how to unroll video
  1. Follow @ThreadReaderApp to mention us!

  2. From a Twitter thread mention us with a keyword "unroll"
@threadreaderapp unroll

Practice here first or read more on our help page!

More from @johnmdudley

Feb 14
Following up my rainbow thread, I starting thinking about the tertiary bow and indeed you can see it on a semi-transparent screen placed behind the glass sphere (i.e. in the same direction as the incident rays). The vertical metal post in the photo blocks the focussed light. Image
Image
So the photo above shows simultaneously primary, secondary, and tertiary bows! Very nice. For completeness, I am going to now show some raytracing pictures for this case of all three caustics. First with one ray comparing ray paths in water and glass. Image
It is easy to scan over the incident angle (impact parameter y/R) and we can use false colour to show the caustics of the primary, secondary, and tertiary bows. Image
Read 5 tweets
Feb 9
Preparing my 2025 Day of Light outreach lectures, I bought a glass sphere and made a rainbow. But I saw some odd things, and so here’s a thread with some photos & raytracing pictures to try to explain what's going on. First the basic setup showing the primary bow. Image
Where is the secondary bow? It took longer than it should have to find it, and it turns out it’s a long way away, nearly perpendicular. An angled screen helps and the secondary is then clearly seen with inverted colours as expected. But why is it so far away from the primary? Image
Moreover, fiddling with the alignment and moving the screen very close to the sphere, I can actually make the secondary bow appear inside the primary! What?? What is happening? Image
Read 14 tweets
Oct 6, 2024
Feynman's QED: The Strange Theory of Light and Matter, was first published in 1985. In response to two completely unconnected queries in the last few weeks, here's a thread on how the lectures on which the book were based were first given in New Zealand. Image
The story begins in 1979 when Feynman gave the Sir Douglas Robb Lectures at the University of Auckland in New Zealand. These talks were a testing ground for his 1983 UCLA Alix G. Mautner Memorial lectures, widely considered to be the basis of the 1985 book.
But Feynman's Introduction to the 1985 book clearly explains that the lectures were first delivered in New Zealand. Image
Read 21 tweets
May 29, 2023
This year is the 600th birthday of the University of Franche-Comté, the 10th university created in France in 1423. For @IDLofficial I gave a talk on optics history here since the science faculty was created in 1845. First batch of tweets follow; text in English, slides in French. Image
The story begins with our project with @SSAC_Univfc to save the lab archives that date back over 100 years. We found many old cans of photographic negatives from the 1970s and one was especially intriguing – who were these "ancestors"?
Image
Image
This single roll of film kicked off a 6 month study! It contained in it a photograph showing portraits of all the Chairs of Physics since 1845! (The dates in the photo show when they occupied their posts in Besançon.) Now for the detective work. Who were they? Image
Read 26 tweets
Dec 6, 2021
To kick off the week, here is an updated (and long!) thread on the history of nonlinear optics. First a real surprise! The explicit use of the terminology “nonlinear optics” can be traced back to Erwin Schrödinger in 1942. Yes you read that right. Schrödinger himself!
Although this paper isn’t really what we would describe today as non-linear optics. Rather it describes “vacuum light-light scattering” or nonlinear QED. But the wording Schrödinger used definitely sounds familiar! It builds on earlier work by Born, Infeld, Euler.
It seems that what Schrödinger and the others were describing was finally observed in 2019 at @CERN @ATLASexperiment Can @jonmbutterworth confirm ?
Read 44 tweets
Apr 3, 2021
I was honored to speak at Moscow State University last week for the 60th anniversary of laser nonlinear optics. But in fact, the first nonlinear effects in optics were observed in the pre-laser era by Vavilov in Moscow in 1926! Here are some slides from my talk (thread).
Sergey Ivanovich Vavilov (Серге́й Ива́нович Вави́лов) was a giant of physics. He invented the term "nonlinear optics" in his 1950 book & was co-discoverer of Cerenkov radiation. Regrettably he died before the Nobel Prize for Cerenkov radiation was awarded in 1958.
Brown and Pike give the translation of how he introduced nonlinear optics in a chapter in the wonderful book Twentieth Century Physics (Eds Brown, Abraham Pais, A. B. Pippard 1995).
Read 14 tweets

Did Thread Reader help you today?

Support us! We are indie developers!


This site is made by just two indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member ($3/month or $30/year) and get exclusive features!

Become Premium

Don't want to be a Premium member but still want to support us?

Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal

Or Donate anonymously using crypto!

Ethereum

0xfe58350B80634f60Fa6Dc149a72b4DFbc17D341E copy

Bitcoin

3ATGMxNzCUFzxpMCHL5sWSt4DVtS8UqXpi copy

Thank you for your support!

Follow Us!

:(