On the boards

A very nice piece by April Peavey about the electro-mechanical flip-flapping annunciator boards that have all but disappeared from American train stations. I now know that they can be called Solari boards, after the Italian manufacturer that first introduced them in 1956. Maybe I realized, but have forgotten, that the letters and numbers flap in only one direction, so that the transition from an E to an H, for instance, takes much less time than for an S to an A—and hence the new destination or train name is displayed one letter at a time, as the individual units cycle around. It’s that gradual reveal that I remember, like watching a photograph develop, or like playing the word puzzle from Wheel of Fortune in real time.

Alas, the news peg for this story is that Amtrak is replacing the Solari board in Philadelphia’s 30th Street Station, where many years ago I would wait for the regional train to New York to take me back to my internship.

Under pressure

Callan Bentley turns the screws on a diamond anvil cell. Pressures inside the cell, a little gizmo smaller than a snow dome, are on the order of 60 GPa. He writes:

  • 60 gigapascals is therefore a pressure equivalent to about 2100 kilometers of depth in the planet – most of the way through the mantle, though not quite to the outer core (which is at ~2900 km depth).
  • A pressure cooker cooks at 0.0001 GPa.
  • Your car’s tires are inflated to a pressure of 0.0002 GPa (2 bars, or ~30 psi).
  • 60 GPa is a lot more than 0.0002 Gpa.

(Sorry, but I had to go to that song.)

I’m with you on the illegible part

In a quite useful five-part series, Steve N.G. Howell explains how field notes work and how and what you might want to record, either in the field or in the motel at the end of the day. He saves the best advice for the last installment:

In conclusion, your notes are your notes. Write what you want, but in later years you’ll only have yourself to blame if your old notes don’t contain the information you find you want. If you have time, write it all down. If you don’t, pick and choose. But whatever you do, or don’t do, the main thing is to enjoy birding.

Halfway down the block before realizing that you’re headed the wrong way

A simple, analog solution to SOSED (Sudden-Onset Subway Exit Disorientation): low-profile wayfinding signs on the stairway risers, designed by Ryan Murphy and documented by Vicky Gan. Much more useful than smartphone beacons, also discussed in the post: who wants to be staring at a screen when you and 1,000 of your new best friends are trying to get off the platform and into the light?

I am relieved

The states of North and South Carolina are completing the resurvey of their common boundary, using high- and low-tech means, as Stephen R. Kelly notes in a recent op-ed and Kim Severson reported some time back. The colonial-era border was intended to consist of two straight lines, the 35th parallel and a diagonal crossing up from the coast. But 18th- and 19th-century surveyors made a hash of it, resulting in today’s rumpled compromise.

The rework was not intended to smooth out any of the coarse wrinkles, like the wobble around the city of Charlotte, but rather to replace the notched trees, now dead, and wandering survey monuments (including one moved by a golf course in order to impress golfers [?!]) that had originally marked the boundary.

But rest assured! South of the Border is still where it “Otto B.”

Two distinct problems

Charles Severance reflects on his experiences teaching MOOCs. In much the same way that John Markoff analyzes the situation (as I summarized earlier), Severance draws an important distinction between the objectives of conventional university training and those of massively open online courses. From the full article (behind a paywall):

My goal in a MOOC is to teach as many volunteer learners as I can and keep them engaged and learning as long as I can. In an on-campus course, my goal is to teach captive students as much as I can over a set 15 weeks. [Emphasis in original.]