The Equation of Time: The Concept and Watches

[@jeffreyblue627]

Well taught Professors! I’ve wondered about this for some time but never bothered to read up on it. Once again Watchartsci is the KZbin master class for all things horological. Thanks again.

[@watchartsci]

It's funny Jeff, it's really a simple concept (difference between watch time and solar time) but not so easy to work out the details! Another fun project for watch collection! Take care, Bill

[@Tuneitupful]

Finally someone who clearly explains the EoT concept to us mere mortals, thanks Bill.

[@watchartsci]

Thanks man! More recently, I got an affordable EoT watch ... kzbin.info/www/bejne/nqHIgGynfZKHfrc ... you might like that too TuneIfUP! Take Care, Bill

[@Tuneitupful]

@@watchartsci Thanks for the link Bill. I I was actually looking into that Longines from your referral from this video.

[@BorisBidjanSaberi11]

Probably my favorite complication, truly a unique mechanism to keep this accurate. Love them

[@watchartsci]

Hi Joe, we just went off Daylight Savings Time, and now I can better check the different functions on my Longines 5235 Ephemerides Solaires... while it was the only Equation of Time watch that I could afford, it turned out to be real gem! Take care, Bill

[@colinubeh1180]

Well with all those complications, we can't expect them to be cheap. I was mesmerized by all the gears in The F.P. Journe Astronomic Souveraine. That is one hell of a craftsmanship. Too bad I can't afford it.😁

[@watchartsci]

Hi Colin! I couldn't afford the FPJ either, but I could afford this with the Equation of Time: www.chrono24.com/longines/longines-1989-ephemerides-solaires-ltd---longines-service-bp--id29608861.htm Take care, Bill

[@canuckwatchcollector8664]

Great video Bill. Great summary of the concept and the range of watches. I imagine watches with equation of time complication would also have a perpetual calendar or an annual calendar at a minimum.

[@watchartsci]

Hi Canuck, you'd think that, wouldn't you. Check out the latest video...😬 Take care,Bill

[@canuckwatchcollector8664]

@@watchartsci Bill, congrats on the Longines. That’s a great idea of the curve on the bezel. I think the 1, 15 and 30 are days of the month. It looks like the progression of sunrise or sunset over the month.

[@simmysharma6845]

👍 very interesting topic. Thanks for sharing, Sir

[@watchartsci]

My pleasure, Simmy. Take care, Bill

[@ericchilver9113]

Thankyou Bill, another informative video, appreciated.

[@watchartsci]

My pleasure Eric! Take care, Bill

[@derekrolle6705]

Love this episode.

[@watchartsci]

Hey Derek! Thanks man! Take care, Bill

[@juniorjohnson5961]

I'm confused I've saved the video & will probably have to watch it a few times . Thanks Bill 🙏

[@watchartsci]

Don't try and grasp it all at once, Junior. Make a sundial for fun. (www.sundials.co.uk/projects) Take care, Bill

[@juniorjohnson5961]

@@watchartsci I'm moving to Kentucky to help Mom & Stepdad they have a big side yard with no trees or anything blocking the Sun I'll set one up there , To many trees & house's at my place . Thanks for getting back means a lot 🙏

[@wysiwyg2489]

The easiest way to understand this: 1. Earth orbit around the Sun is elliptical, not circular. 2. Earth rotation axis is at an angle relative to its trajectory. Humans developed the tracking of time as a regular division of the yearly rotation around the sun (365 days), this is what Bill is calling main (average) time. When accounting for items 1 and 2, the actual position of the sun does not match what our watches are displaying (the difference can be up to 15 min as Bill showed). Since this difference is cyclical, and everybody uses main time, there is no problem or need for adjustments. Similar thing happens when considering a year, there is a difference between our main and real time of approx. 6 hours. This is compensated every 6 years by adding a full day to our calendars.

[@Javi_C]

Much appreciated, thank you for the lesson Dr.!

[@watchartsci]

My pleasure Javi.. I got to build a sundial. Take care, Bill

[@AbdulRWatches]

I always wondered about the equation of time complication. Great explanation and demonstration Bill, very informative and understandable. Thanks again for always enlightening us with these horological topics. Cheers, Abdul

[@watchartsci]

It's hard to find an affordable EOT watch Abdul, and this one seems to be just right in terms of just about everything for what I need. Working out the EOT with the blue parabola around the bezel is oddly informative. Take care, Bill

[@Snorkelsnot]

Outstanding presentation! I’ll seriously consider getting one of those. Thank you for calling it to our attention. I didn’t know they existed.

[@watchartsci]

Hi Snorkels, very glad you liked it. Just another fun thing about watch collection. Take care, Bill

[@washingtonfootballfanwgil8392]

Bill, Just this year, I hand a chance to buy the Martin Braun EOS and I passed on it for another watch. Now, I wish I went with the EOS to add a dimension to my collection.

[@watchartsci]

Well, Fan, you're not alone! Not all of the MB EOS models are also EOT... some just have the sunrise and sunset....which in itself is not mean task! Take care, Bill

[@chrishoyt7548]

Great vid Bill. Nice plain shirt. Chris

[@watchartsci]

Thanks Chris! A plaid shirt and a discussion of the Equation of Time ... what more could I possibly want? Take care, Bill

[@xpdchief7698]

Great video Bill, very informative. This is the first video I’ve watched where the presenter designed/built both of the instruments used in the video. I’ll say it again, I learn something every time I watch one of your videos. Best regards, Brian

[@watchartsci]

Brian, you know all the fun things you get to do once you retire! Here's the link: www.sundials.co.uk/projects. Take care, Bill

[@leightodd7335]

Thanks Teach! Can't wait to enlighten the Fracking Gulch Mensa Club. Holy Moley that JP watch is spectacular. Although I can't imagine what the service cost would be after my May Day party?

[@watchartsci]

Anything for the FGMC, Leigh. The cam of some of these watches have the same shape as determined by some of the Ancient Greek astronomers. Take care, Bill

[@pw3554]

Very nice video! Well done!

[@watchartsci]

Glad you enjoyed it PW! Take care, Bill

[@markocecek9703]

Thank you for another interesting video Mr. Sanders. Perhaps you could someday also make a video on temporal hour watches. I have once stumbled upon an interesting Japanese watchmaker Masahiro Kikuno who build a temporal hour wristwatch (Wadokei). Very interesting watch.

[@watchartsci]

Thanks Marko, I'll have to learn about temporal hours now! Take care, Bill

[@mohamedazkoul9544]

Thanks for your video Bill , i remember stuyding about this complication, there are 4 Days where the Solar time matches the means time ..april 15th , June 14th , September 1st and December 24th we had this JD watch i have to say it's pretty impressive ..was limtied edition with enamel dial.

[@watchartsci]

Wow, you got the math right Mohamed! Take care, Bill

[@mohamedazkoul9544]

@watchartsci thanks a lot , I prefer your explanation much easier that the brands training really , if I may ask you do you have any Video about the Bi-axial and tri-axial tourbillon ?

[@watchartsci]

No I’m afraid not Mohamed.

[@oliverkuno8679]

I have the GP EOT and love it, but it is difficult to adjust by the watchmaker

[@watchartsci]

It's a very complex movement Oliver! Take care, Bill

[@LeonXOV]

Very informative video. However I’m curious that what is the cheapest EOT watch available in the market right now?

[@watchartsci]

Leon, probably the best way to find the most affordable EOT is with a Google search; however , the Longines 5235 Ephemerides Solaires is a good bet. Let me know what you find! Take care, Bill

[@derricksmigh1665]

Sir, you are in my humble opinion the most in depth and fun watch critic. Can you show the operation and or how the Longines ephemerides solaires? This is one of my grails but Im nervous to pull the trigger because i dont know what options and feathure the Longines has. I can not find videos on it anywhere. Or if you could point me to a video in english

[@watchartsci]

Hi Derrick, just this week I did this video [kzbin.info/www/bejne/nqHIgGynfZKHfrc] that explains how the different features of Longines Ephemerides Solaires work...but some I still have not yet fathomed. Take care, Bill

[@dominickcolasanto6582]

Great video Bill always wanted to know exactly what EOT was I had my guess now I know exactly. Very interesting and included in some of your choices was sun up sun down another uncommon but useful function. Thanks have a great day.

[@watchartsci]

Hey Dom, thanks man. It may sound strange but making that sundial was one of the more informative (for me) projects ... here's the link: www.sundials.co.uk/projects Take care, Bill

[@dominickcolasanto6582]

@@watchartsci Bill thanks for the link

[@GS_Superman]

Excellent video…probably the most simple explanation of EOT, which is hard to do with this complex topic.

[@watchartsci]

Thanks Superman! It's both simple and complex at the same time. Making a sundial is fun too! Take care, Bill

[@Snorkelsnot]

Hi Bill, I have a “SUNWATCH” which is a 2 x 3 inch pocket sundial with 3 bands for reading the time for 30, 40 and 45 degrees respectively. The fold over lid shows variation, correction minutes by location and dates for approx 50 US cities. I’d send a picture but don’t see a link for photos. Great fun for people like me with no need what-so-ever for accuracy to seconds per month or even years!😊

[@watchartsci]

Snorkels, does it look something like this one? www.1stdibs.com/furniture/more-furniture-collectibles/collectibles-curiosities/scientific-instruments/sundial-compass-case-bronze-bion-nicholas-paris-18th-century/id-f_28947272/?allowUniversalLink=no&gclsrc=aw.ds&gclid=Cj0KCQjw4omaBhDqARIsADXULuWmUCRdTSknGiD6fdASboPfofeHiYRvqSi3nCIET8DRYu_KdWxmky0aAlFWEALw_wcB&gclsrc=aw.ds Take care, Bill

[@Snorkelsnot]

No,similar perhaps. I found a KZbin video of it astonishingly enough called: 1920’s Boy Scouts of America Sunwatch. By Roger Dignard. According to the directions you have to adjust for both the day of the year and location since your city probably isn’t right on one of the provided latitudes. (I used to carry out my calculations to at least 3 decimal places - now I laugh at my old self and while just am or pm doesn’t quite cut it, a few minutes off makes no difference anymore; it’s all good.)

[@wcottee]

Maybe I missed it but is it true that 12:00 solar time occurs when the Sun is at the observer's prime meridian (i.e. due south)? BTW, it is amusing that one would spend 200K for a watch that tells them how to read a sundial...but hey, if you can afford it more power to you😆!!!

[@watchartsci]

So many possibilities to straighten out Wcottee. Take care, Bill

[@alanwright3172]

Two questions 1, Is that Magnetic North or True North? 2, Does this take into account the eight min delay on the sun's apparent position as opposed to its' actual position in space?😁 Seriously well explained vid Bill thanks.

[@watchartsci]

Alan, that's a good question, and I'm not certain. I believe it's True North. You've been elected the Horological Investigator! See what you can find out. Thanks man! Bill

[@alanwright3172]

@@watchartsci Actually it is True North, and as for the eight minutes I think we should call it "Apparent Solar Time" 😂 I think this is a fantastic complication but has no real purpose rather like the tourbillon on a wrist watch. One day my piggybank might be big enough to buy the FP Journe😁

[@watchartsci]

@@alanwright3172 Thanks and I'll take a glance for Apparent Solar Time rather than finding what the time was 8 minutes ago.😉

[@lousyshot1]

Great video Bill! Do the flat earth folks agree with this science?

[@watchartsci]

Nah, Lousyshot ... flat earth people: Hated it! That's a good sign. Take care, Bill

[@lousyshot1]

@@watchartsci I checked on several different watches and prices are really up there.

[@watchartsci]

@@lousyshot1 www.chrono24.com/longines/longines-longines-5235-rare-ephemerides-solaires--id24993706.htm

[@kestonwright9881]

Grest video

[@watchartsci]

Hey Keston, thanks man! Take care, Bill

[@jdc1957]

Outstanding.

[@watchartsci]

Thanks JDC! Take care, Bill