Re: Gnomon Gap Puzzle

Happy New Year, Frank, How about a T-shaped dial consisting of a vertical east dial backed by a vertical west dial and sharing a solid sloping roof whose edges act as the gnomons. The hour lines close to noon could be marked as a horizontal dial on the "floor" of the dial. I think that this

Re:

I used to subscribe to the CALNDR-L mailing list but I gave it up because I did not have time to consider the numerous fascinating postings. It seems to be still available at: http://myweb.ecu.edu/mccartyr/calndr-l.html Geoff 2018-04-13 14:43 GMT+01:00 graham stapleton via sundial <

Re: Hail to the Chief

Dear Frank, Can I help the POTUS? No. Can I answer your question? Maybe but I am not used to working in imperial units. Consider a horizontal cross section of the gnomon at any height above the dial plate. The shape of the section would be an ellipse with minor axis equal to 0.5" aligned

Re: Golden Ratio and Sundials

> mathematical language of beauty. Was AUD $2. $2 to get you to purchase the > 1st book. And then you may want to purchase the series of books. Of course > they will not $2. > > Regards, > > Roderick Wall. > > - Reply message ----- > From: "Frank King" <f...

Re: Golden Ratio and Sundials

Frank, I think the most elegant proof that the diagonal to side ratio in a pentagon equals phi is as shown in the attachment. Geoff On 23 June 2017 at 08:08, Frank King wrote: > Dear All, > > Referring to the Golden Ratio and Sundials, Donald > Snyder wrote: > > I see

Re: Sundials that come with 'baggage'.

Just a guess, but might San 1790 be a misinterpretation of F.an 1790 (an abbreviation of Fecit anno 1790). This would then match Mrs Gatty's description pretty well. Geoff On 20 June 2017 at 10:53, Patrick Powers wrote: > Hello all, > > It’s always interesting to

Re: Capuchin and Regiomontanus dials

Michael, I seem to recall that sec^2(x)=1+tan^2(x) Therefore sec^2(lat).sec^2(dec)=(1+tan^2(lat)).(1+tan^2(dec)) =1+tan^2(lat)+tan^2(dec)+tan^2(lat).tan^2(dec) =(1+tan dec tan lat)^2 + (tan dec - tan lat)^2 I guess that this relationship, which is just a variant of sin^2+cos^2=1, should have

Re: The duration of the year

Doug, 1. You could do what the Egyptians and the Greeks did 1500 years earlier. Use a mural quadrant in the meridian to establish the greatest and least altitude of the noon sun ( from this you could calculate the orbital inclination and your latitude) and mark the mid altitude. You

Re: Unusual bi-annual sundial

Thank you, Frank, for that comprehensive analysis of the problem. However, I wonder if the errors might be masked by the 32 arc minute solar penumbra. Best wishes, Geoff On 19 January 2017 at 16:33, Frank King wrote: > Dear John, > > I wondered when someone would spot that

Re: Leap Second Quiz Question

Happy New Year to one and all, The University Clock has gained 0.5 seconds against UTC in the past week but is now 2.0 seconds ahead of UTC because of the leap second. If Frank removed coins in accordance with the LWG for 0.5 seconds, then the clock's rate would be rectified but the clock would

Re: Sundial Puzzle Corner

I like David's solution and I am in awe of his stone-cutting capability. However, to return to your problem where the ellipse has been returned without any markings, why not draw an ellipse of the same specified dimensions on paper with the axes already marked on it? This could then be matched to

Re: Sundial Puzzle Corner

Frank, Thanks for the puzzle. I think that these instructions might work if you ventured to the antarctic circle during the southern winter and then trecked to a position such that your latitude is greater than 90-Dec (so that the midnight sun is visible) but less than 90. The shadow of the stake

Re: Using analemmatic sundials for determining sun exposure times

Thanks for the mental exercise, Frank. I think that Willy might squeeze another 15 seconds of illumination at the end of December owing to the rapid change in the EoT. A useful graph showing the rate of change of EoT is provided by the USNO at: http://aa.usno.navy.mil/faq/docs/eqtime.php Geoff