Re: EoT diagram
Dear Kevin, I was interested in your comments on EoT. I agree that the kidney curve is not very pretty. You would be happier if we could go back to the year 1246 when the analemma had mirror symmetry about its long axis. This would tidy up the kidney a little! You say... > ...the master of all mechanical EoT > generators must be the device in the > Strassburg cathedral clock. You overlook the mechanism in the Jens Olsen World Clock in Copenhagen. This clock calculates the EoT using a long train of gear wheels. Essentially you have a digital calculation in a pre-digital era, ca. 1940. All mechanical representations of the EoT suffer from a fundamental defect: the EoT keeps changing year on year, albeit slowly. This applies to any once-off analemma too of course. The Jens Olsen clock is in the City Hall in Copenhagen and is open to the public BUT I have a... HEALTH WARNING: Visiting this clock is likely to cause instant addiction. I went in at opening time one morning and had to be prised out of the building at closing time! All the best Frank --- https://lists.uni-koeln.de/mailman/listinfo/sundial
time, off topic
During Darwin's famous voyage aboard the "Beagle", Captain Fitzroy had 22 chronometers aboard, no doubt to obtain accurate longitudes. This seems pretty excessive and I'm wondering how many (or few) chronometers would have reduced his time errors to an acceptable level. Any thoughts? Poisson distribution, perhaps? Frank 55N 1W --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: time, off topic
Fitzroy was the geek of his time - he was rich enough to own 22 chronometers and he was interested in everything - (especially meteorology - hence the Shipping weather forecast zone called after his name and the Fitzroy Storm Glass) A 'normal' naval ship in those days carried three chronometers - the average of the two which showed the closest time was used to compute longitude Best regards Kevin Karney Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales, UK 51° 44' N 2° 41' W Zone 0 + 44 1594 530 595 On 23 Jun 2011, at 09:51, Frank Evans wrote: > During Darwin's famous voyage aboard the "Beagle", Captain Fitzroy had 22 > chronometers aboard, no doubt to obtain accurate longitudes. This seems > pretty excessive and I'm wondering how many (or few) chronometers would have > reduced his time errors to an acceptable level. Any thoughts? Poisson > distribution, perhaps? > Frank 55N 1W > --- > https://lists.uni-koeln.de/mailman/listinfo/sundial > --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: time, off topic
Dear Frank, To add to Kevin's reply I have a contact at Greenwich Observatory who replied to my amazement that there were that many chronometers on board, and said: Dear Doug, Yes there were that many, not all were government, if I remember properly 5 were Fitzroy's own, 2 were loaned by makers who wanted them trialled in effect and 16 were government. Beagle was on a long trip of which surveying was one of the prime objects. Surveying vessel if a way for years ( in the South American surveys some 14 years was spent doing them and vessels were away years (7). I can give you more exact data when I am in the Observatory plus my own books on surveying. Remember they used to rate them by the astronomical methods when doing in shore surveying with shore bases set up. I can relate some of things that were done when the Australia coast was surveyed by Stokes (served in Beagle for 14 years on surveying and took Beagle to Australia) I have the definitive books on the Australian surveys (a lot of coast line!!).. Best Regards, Peter I can add that almost certainly some may have been on test and although chronometers are generally reliable, some could well fail on a long trip. Regards, Doug On 23 Jun 2011, at 09:51, Frank Evans wrote: > During Darwin's famous voyage aboard the "Beagle", Captain Fitzroy had 22 > chronometers aboard, no doubt to obtain accurate longitudes. This seems > pretty excessive and I'm wondering how many (or few) chronometers would have > reduced his time errors to an acceptable level. Any thoughts? Poisson > distribution, perhaps? > Frank 55N 1W > --- > https://lists.uni-koeln.de/mailman/listinfo/sundial > --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: EoT diagram
On Thursday, June 23, 2011 9:33 AM, Frank King, commenting on Kevin Karney's posting, said > > ...the master of all mechanical EoT > > generators must be the device in the > > Strassburg cathedral clock. > > You overlook the mechanism in the > Jens Olsen World Clock in Copenhagen. > > This clock calculates the EoT using a > long train of gear wheels. Essentially > you have a digital calculation in a > pre-digital era, ca. 1940. > > All mechanical representations of the > EoT suffer from a fundamental defect: > the EoT keeps changing year on year, > albeit slowly. This applies to any > once-off analemma too of course. > How about the Meccano mechanisms shown to us in Newbury by Patrick Briggs a few years ago? Stunning what can be done with a few off-the-shelf components. Brilliant use of Hooke's joint to model the obliquity element. I haven't studied the Copenhagen Town Hall clock but am surprised you say it is digital. Gears, although limited to an integral number of teeth, are essentially analogue devices, aren't they? The cardboard orreries sold by Leonard Honey even overcome that limitation by using drivebelts. It isn't clear to me that all mechanical representations suffer from a fundamental defect - Kevin has shown us (at a BSS Conference) a copy of the EoT cam from the Clock of the Long Now (I may have the name slightly wrong, sorry) which takes the long-term variation into account. And I'm sure the same thing could be done in other ways, if anyone had the inclination. Chris 51.3N 1.3W --- https://lists.uni-koeln.de/mailman/listinfo/sundial
E o T diagram
Beautiful shapes and history. My E o T diagram: https://picasaweb.google.com/mgarrando/ECUACIONDETIEMPO?authkey=Gv1sRgCIDLsd zsp52i_AE#5621470247522825746 Best wishes Miguel A. G. Arrando <>--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: E o T diagram
I do not know the answer to this question: Looking at the intersections of the EoT and Mean Time curves in M. Garcia's diagram, is there any reason to conclude that the area of the intersections outside the mean time curve must equal the area of the intersections inside the mean time curve? The areas look similar. My initial hunch is no, but I do not see how to readily prove or disprove this. -Bill On 6/23/2011 1:27 PM, Miguel A. Garcia wrote: https://picasaweb.google.com/mgarrando/ECUACIONDETIEMPO?authkey=Gv1sRgCIDLsdzsp52i_AE#5621470247522825746 --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: EoT diagram
Dear Chris, As always, you prompt further thought... > Gears, although limited to an integral number > of teeth, are essentially analogue devices, > aren't they? Er, not sure :-) In earlier days, I spent many a happy hour looking at clocks and counting teeth. That felt like a digital experience at the time but it may have been analogue after all! You (citing Kevin) are right that the Clock of the Long Now has an extended cam which takes long-term changes in the EoT into account. With that kind of feature, you can deal with most of the more obvious parameters like the EoT, obliquity, eccentricity and so on, for a long time to come. The one thing such mechanisms can't handle, because we simply can't predict it, is the tiresome matter of the length of the day... We can see the general trend but there is horrid superimposed noise which means we cannot predict leap seconds very far ahead. The Clock of the Long Now deals with this by poking its head above ground at intervals to check the sun. If gear wheels are analogue, then maybe the Clock of the Long Now is really a sundial? I think you are onto something :-) All the best Frank --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: E o T diagram
Hi Miguel, Your EOT diagram is good. I like how you can count the minutes to add or subtract. Do you have one that is in English? Roderick Wall. -Original Message- From: Miguel A. Garcia Sent: Friday, June 24, 2011 3:27 AM To: sundial@uni-koeln.de Subject: E o T diagram Beautiful shapes and history. My E o T diagram: https://picasaweb.google.com/mgarrando/ECUACIONDETIEMPO?authkey=Gv1sRgCIDLsd zsp52i_AE#5621470247522825746 Best wishes Miguel A. G. Arrando --- https://lists.uni-koeln.de/mailman/listinfo/sundial - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1382 / Virus Database: 1513/3716 - Release Date: 06/20/11 --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: E o T diagram
Hi Miguel, I keep getting an error message (404 Bad_Request) from picasa :^( best wishes, Peter On 24/06/2011 02:57, Miguel A. Garcia wrote: https://picasaweb.google.com/mgarrando/ECUACIONDETIEMPO?authkey=Gv1sRgCIDLsd zsp52i_AE#5621470247522825746 -- -- Peter Mayer Politics Department The University of Adelaide, AUSTRALIA 5005 Ph : +61 8 8303 5606 Fax : +61 8 8303 3443 e-mail: peter.ma...@adelaide.edu.au CRICOS Provider Number 00123M --- This email message is intended only for the addressee(s) and contains information that may be confidential and/or copyright. If you are not the intended recipient please notify the sender by reply email and immediately delete this email. Use, disclosure or reproduction of this email by anyone other than the intended recipient(s) is strictly prohibited. No representation is made that this email or any attachments are free of viruses. Virus scanning is recommended and is the responsibility of the recipient. --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: E o T diagram
Hi Miguel, I've just succeeded! The URL works with Internet Explorer, but not with Firefox. A very useful and visually striking version of the EoT. Thank you. Peter On 24/06/2011 02:57, Miguel A. Garcia wrote: Beautiful shapes and history. My E o T diagram: https://picasaweb.google.com/mgarrando/ECUACIONDETIEMPO?authkey=Gv1sRgCIDLsd zsp52i_AE#5621470247522825746 Best wishes Miguel A. G. Arrando --- https://lists.uni-koeln.de/mailman/listinfo/sundial -- -- Peter Mayer Politics Department The University of Adelaide, AUSTRALIA 5005 Ph : +61 8 8303 5606 Fax : +61 8 8303 3443 e-mail: peter.ma...@adelaide.edu.au CRICOS Provider Number 00123M --- This email message is intended only for the addressee(s) and contains information that may be confidential and/or copyright. If you are not the intended recipient please notify the sender by reply email and immediately delete this email. Use, disclosure or reproduction of this email by anyone other than the intended recipient(s) is strictly prohibited. No representation is made that this email or any attachments are free of viruses. Virus scanning is recommended and is the responsibility of the recipient. --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: time, off topic
Good afternoon Frank, Although I failed statistics as an undergraduate, I later became fairly good at it when I was involved in research. My memory seems to recall that the minimum number of samples for a reasonable approximation of a normal distribution was in the low twenties. But as I haven't had to worry about minimum sample numbers for a while (my current set is > 5,000), I may well be incorrect on this. Doubtless someone else on this list will gently correct me! But would Fitzroy really have known much about statistical distributions? Perhaps more likely he was taking multiple backups, plus a few freebies? During my field work I have learnt the hard way about backups. A notebook computer completely died on me in the middle of outback Queensland, and I had to spend hours reloading Windows and essential software. Now I travel with two notebooks, two GPSs, etc. And this is for trips of only a few months. If I'd been Fitzroy on a research voyage of several years, I'd have made very sure I wasn't going to have chronometer problems Cheers, John John Pickard john.pick...@bigpond.com - Original Message - From: "Frank Evans" To: "Sundial" Sent: Thursday, June 23, 2011 6:51 PM Subject: time, off topic During Darwin's famous voyage aboard the "Beagle", Captain Fitzroy had 22 chronometers aboard, no doubt to obtain accurate longitudes. This seems pretty excessive and I'm wondering how many (or few) chronometers would have reduced his time errors to an acceptable level. Any thoughts? Poisson distribution, perhaps? Frank 55N 1W --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: E o T diagram
Hi Peter, I copied and pasted the link into my web browser. But make sure you also copy/past the 2nd line. Roderick. -Original Message- From: Peter Mayer Sent: Friday, June 24, 2011 10:37 AM To: Miguel A. Garcia Cc: sundial@uni-koeln.de Subject: Re: E o T diagram Hi Miguel, I keep getting an error message (404 Bad_Request) from picasa :^( best wishes, Peter On 24/06/2011 02:57, Miguel A. Garcia wrote: https://picasaweb.google.com/mgarrando/ECUACIONDETIEMPO?authkey=Gv1sRgCIDLsd zsp52i_AE#5621470247522825746 -- -- Peter Mayer Politics Department The University of Adelaide, AUSTRALIA 5005 Ph : +61 8 8303 5606 Fax : +61 8 8303 3443 e-mail: peter.ma...@adelaide.edu.au CRICOS Provider Number 00123M --- This email message is intended only for the addressee(s) and contains information that may be confidential and/or copyright. If you are not the intended recipient please notify the sender by reply email and immediately delete this email. Use, disclosure or reproduction of this email by anyone other than the intended recipient(s) is strictly prohibited. No representation is made that this email or any attachments are free of viruses. Virus scanning is recommended and is the responsibility of the recipient. --- https://lists.uni-koeln.de/mailman/listinfo/sundial - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1388 / Virus Database: 1513/3722 - Release Date: 06/23/11 --- https://lists.uni-koeln.de/mailman/listinfo/sundial
