This is the pertinent part of the book:
A pleated bridge. Yes?
Reminds me of the old paradox:
An ant starts to crawl along a taut rubber rope 1 km long at a speed of 1 cm per second (relative to the rubber it is crawling on). At the same time, the rope starts to stretch uniformly at a constant rate of 1 km per second, so that after 1 second it is 2 km long, after 2 seconds it is 3 km long, etc. Will the ant ever reach the end of the rope?
The answer, of course, is counterintuitively yes.
Interesting that I had remembered the passage as referring to an “ant,” whereas the text just says “small insect”… but the picture is definitely that of an ant. On the other hand, I remembered it as being a dress, whereas both the 90-second film and the 2018 film trailer use a string. The text says it’s a skirt. The picture looks like a string but presumably we’re meant to think of the cross-section.
Which ultimately derives from the fact, well-known to mathematics students, that the harmonic series diverges.
Yes, literally 
The details are not evident, though. It took me some concentration to follow the wikiexplanation.
Sorry it wasn’t helpful - I just find it very funny and couldn’t resist posting it.
I’m sure I’ve never heard of L’Engle nor her books. But thanks for the vector.
Nothing says “Los Angeles” like a concrete-lined drainage canal with a few inches of water running through flat land with low mountains in the distance and an avante-garde bridge in the foreground.
Dayum I miss living there.
Somewhat disappointed there was no reference to box girder bridges, or card games!
The only thing it’s missing is Arnold Schwarzenegger riding a Harley and firing a shotgun one-handed.
“Drainage canal”? Good sir, that’s the mighty Los Angeles River! Harrumph.
/faux outrage
The Sundial Bridge featured in a problem we did in my precalc class.
I didn’t. Never read the stories.
I would have recognized it if had been a Holtzman bridge, but the lack of Guild Spacers might make the bridge untenable.
Many’s the time I drove over the mighty LA river on the 10 just east of downtown and passed the equally mighty Brew 102 brewery. Which Google Streetview suggests has now been submerged beneath the sands of time.
So are there paddlewheel steamer dinner cruises or Viking river excursions on the mighty Los Angeles river? Asking for a friend.
You can pack a lunch while kayaking.
When I and my family first moved to Minneapolis, I was a bit miffed to discover that the “St Anthony Falls” are today basically a concrete spillway:
Possibly if they used something like this:
That looks dangerous as hell. The hydraulic jump at the end is exactly the sort of thing that could trap a boat/kayak/etc. in recirculating currents. And it’s wide.
It appears there’s a row of floats and cable 1/4mi upstream to stop people from approaching from above. And directly below that is a rapids and small basin, then another similar smaller dam & lock facility. Well downriver (1/2 mi or more) is about where it starts to become a place safe enough for small boats.