An Equatorial Heliochronometer

Coconuts · Post by **Coconuts** » Sat Feb 23, 2013 12:03 pm

Aka: "Sundial". Growing up on the beach in Atlantic City, I used to make simple sundials by sticking popsicle sticks in the sand at the right angle. I've meant ever since to make a proper sundial, and the lower lawn at Coconuts provided a very fitting location. I did most of the brass machining, rolling, and CNC time strip engraving back home, but dug, hand-mixed, and cast the footing, base, column, and crown while at Coconuts, using light-weight plastic molds that I found online. My first footing had to be moved over by ten yards, as I realized the next day that the Flamboyant would shade it on winter mornings. Time is read, with one minute graduations, by the shadow cast by a brass rod (the gnomom), against the engraved time strip, and once the polar alignment is tweaked, it should be accurate to about a minute.

As it happens, the sun is not the most reliable of clocks; due to the tilt and the ellipticity of the Earth's orbit, even the best sundial will run fast or slow by up to 16 minutes during the course of a year. The corrections to address this constitute the "Equation of Time", which some of you may recall as that enigmatic lazy figure-eight off in the Pacific on globes of the Earth. The Equation of Time was first captured visually in a brilliant multiple exposure photograph (one year in the making) by Dennis di Cicco, back in 1978-79 (attached below). To implement the correction for the Equation of Time, the brass time strip slides left to right on teflon guides within a slot that I machined into the brass equatorial arc. A knob and a brass wire are attached to the right-hand end of the time strip, and guests simply align the wire with the current month on a small EOT graphic to calibrate the sundial. A laminated paper EOT is there for now, but this quickly bleaches under the tropical sun, so I'm CNC engraving a brass version to be installed during our next visit. I'm not sure if there are any math geeks on this forum (cocosmom?), but FWIW, I've attached a copy of the spreadsheet that I wrote to calculate the Equation of Time.

We're really pleased with how the sundial came out; this objet d'art et science adds an elegant touch to our lawn. A small brass plaque on the landing of the stairs to the lawn reads "Le Jardin du Temps".

: Sundial I

: Sundial II

: 11:16 AM

: Dennis di Cicco's Analemma photograph

: Equation of Time calculation

All the best,

Kevin

loria · Post by **loria** » Sat Feb 23, 2013 12:07 pm

cool! have you ever read about or been to jantar mantar? you might find it a very interesting site (in Jaipur, India)

Coconuts · Post by **Coconuts** » Sat Feb 23, 2013 12:17 pm

Loria: No, I have yet to make it to India, although I have seen photos of the remarkable sundials and other astronomical constructions there.

Kevin

Agent99 · Post by **Agent99** » Sat Feb 23, 2013 12:22 pm

Oh my gosh- that is beautiful!

Nancie-Pa · Post by **Nancie-Pa** » Sat Feb 23, 2013 4:21 pm

Wait a minute...you live in beautiful New Hampshire, own a villa on our beloved St John AND you're smart enough to make a cool sundial! Okay, now you're just showing off!

Seriously though, that is one piece of lawn art that is beautiful and interesting. Well done!

toni · Post by **toni** » Sat Feb 23, 2013 5:32 pm

Wow, and you made a 3D map of STJ too! Very very impressive

Thanks for sharing.

Knolmom · Post by **Knolmom** » Sat Feb 23, 2013 5:48 pm

And hoping not to be irreverent or disrespectful, you spent your childhood in AC and didn't grow up to be a Craps Dealer!

mindehankins · Post by **mindehankins** » Sat Feb 23, 2013 7:07 pm

It's beautiful. And looks like it's sitting on the exactly perfect 12" of earth that it was meant for.

mbw1024 · Post by **mbw1024** » Sat Feb 23, 2013 8:43 pm

Looks really cool. Didn't realize you were from Jersey.

cocosmom · Post by **cocosmom** » Sun Feb 24, 2013 5:57 am

[/quote] I'm not sure if there are any math geeks on this forum (cocosmom?), but FWIW, I've attached a copy of the spreadsheet that I wrote to calculate the Equation of Time.

Very cool! I confess to the math geek reference ...been up since 5:00 AM looking up new math lessons BEFORE checking the forum and spice cam...now that proves it.

Need you to stop in Annapolis and teach a sundial lesson!

ski2play · Post by **ski2play** » Sun Feb 24, 2013 7:52 am

love this!

acaldaroni · Post by **acaldaroni** » Sat May 03, 2014 9:09 pm

How freakin' cool is this! I use Star Walk (android / iphone app) to monitor the movement of the stars / sun / planets for astrophotography - I'd much prefer to harken back to the analogue days of reading an equatorial heliochronometer! Awesome Kevin!

sailorgirl · Post by **sailorgirl** » Sun May 04, 2014 8:20 pm

Sheldon Cooper visits the rock!

PointPeeps · Post by **PointPeeps** » Sun May 04, 2014 9:01 pm

Kevin,
If you are on island when we get to Coconuts, would you like this Jersey Shore Gal to bring some White House subs for ya?

Coconuts · Post by **Coconuts** » Sun May 04, 2014 10:01 pm

Pointpeeps: That would be awesome! A lot has changed in AC over the years, but the White House Sub Shop has been there through thick and thin. Make it a Special, and a whole, not a half! I grew up on Illinois Avenue, first one block from the beach, and later two. The majestic Traymore Hotel (postcard below) was on the boardwalk at Illinois Avenue, but alas, was imploded in 1972. In the opening sequence of Boardwalk Empire, as Nucky (Buscemi) turns away from the ocean, a very convincing CGI Traymore appears, and really tugs at my memories. My great uncle Edward Bader served as mayor of AC during the Roaring Twenties, and appears in season one of BE, albeit as a corrupt front man for Nucky.

Sailorgirl: Ouch! I haven't watched the series, but Wikipedia describes Sheldon as having "an almost total lack of social skills, a tenuous understanding of humor, and he experiences difficulty recognizing irony and sarcasm in other people, although he himself often employs them. He exhibits highly idiosyncratic and narcissistic behavior and a general lack of humility or empathy". Check on the Physics bit, but MIT, not Caltech, and I'm reasonably sure the differences run deeper. One can, I hope, be both a geek and a mensch.

: The Traymore

All the best,

Kevin

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