It is a Friday afternoon, and California is experiencing another heat wave. It is not as hot as a few weeks ago, with temperatures well in the 100s/40s, but my daily bike routine, three miles uphill on Allen Avenue, is a continual challenge. It has been an exciting week.
Leonard Cohen’s Popular Problems sounds through my speakers, and his newest record is a true beauty. I’m especially fond of Did I Ever Love You, with its raw bluesy verse and uptime chorus. Magnificent.
Newton has truly surprised me this week. I cannot go into too much detail yet, but I might have unravelled part of a very large Newtonian knot. The true test of that will be the forthcoming Newton Conference, here at the Huntington Library (see here for the program with all details), and I hope my findings will hold. Fingers crossed.
Last week I had a lovely hike in the San Gabriel mountains. I took my chances to scale at least part of the nearby Eaton Canyon trail, enjoying the tranquility of Henninger Flats. Sometimes the mind needs to rest.
The Huntington’s Dibner collection is truly remarkable – I come across so many interesting materials, and really have to limit myself: I need to finish a paper, and soon!
But I would love to share just one of those niceties for now: Newton’s burning mirror.
In a memorandum of 19 May 1704 , the Scottish mathematician David Gregory writes:
M. Geoffrey writes from France, that by a Large Lens the Sun’s beams reduces Gold to a transparent Sky coloured Stone or Glass. This was the occasion of Mr. Newtons 7 Mirroirs. One of these melts silver. It is very nice to sett them by the Sun’s beams; they so burn every thing that is put in the Focus to try. He has another Mirrioir to cast down the Rays again for conveniency.
And in another memorandum, dated July 1704, we find:
Mr. Newtons 7 mirroirs may be sett, so as to have one common focus, conveniently, without hazard of burning, by the Moon. In July 2014 it was tryed. The first time (it being a moist day, tho the Sun shone out) the effects were not so considerable. Afterwards they were very surprizing. Any thing that is greety or dusty is immediately vitrifyed as slate, mettal in powder &c. I saw slate so vitrifyed by it. White paper resists much, unless there be some speck in it. Silver resists more than Gold. Gold after a litle boyling up into Bubbles, flyes out into litle round Gold spherules, & leaves hairs behind it. Gold & other metalls smoak much; & if they are let cool, they smoak again, &c. The midle mirroir is an inch retired backward, which increases the force much. The focus is about the bigness of a Goose Quill.
Who would have thought Newton liked to play around and burn things? He evidently enjoyed it, because there is even mention that he “intends 12 other mirroirs round the 7 that are sett already, in all 19. These will double the effect.” The only missing is a direct quote with Newton saying: I call it my “Death Star”….
Next time: more adventures from Huntingtonland, and and interesting clock in the bargain.