Hi Peter, Patrick et al, I've had a brief look at the patent which, by the way, dates from 1953. It is, as you supposed, an azimuth dial. The two shadow-casting strings, f, are horizontal, one above the other. The ring, d, must be turned until their shadows coincide, in other words when they indicate the sun's azimuth. The "time" is then indicated on an equiangular scale that is carried by a compass needle, so 12:00 is always on magnetic North-South. So, as a sundial, it is very primitive. Its only sophistication lies in the way the time shown can be offset to indicate any desired timezone. But the time shown will be accurate only at noon, as it supposes that the sun's azimuth changes by 15 degrees per hour. When I first saw the diagram I imagined it was a bifilar dial. I think you really could make a passably accurate portable bifilar dial in a very similar manner, but this is not it. Regards Chris 51.4N 1.3W
----- Original Message ----- From: [email protected] To: [email protected] Sent: Tuesday, March 02, 2010 8:48 PM Subject: Re: Would this dial work? For those having difficulty accessing the URL a better one for this would be: http://www.freepatentsonline.com/2637108.pdf Regards Patrick -----Original Message----- From: Peter Mayer <[email protected]> To: 'sundial list' <[email protected]> Sent: Tue, Mar 2, 2010 2:05 pm Subject: Would this dial work? Hi, A while ago I came across US Patent 2637108 for a sundial watch by Viesturs(http://www.freepatentsonline.com/2637108). The patent charmingly suggests that it may be used 'for play and sport, where a good mechanical watch is endangered by pressure, sand and water, and therefore not always adapted to be carried around. As play and sport are mostly exercised during sunny weather, a portable sundial can well replace a mechanical watch on these occasions". As may be seen from the copy of the illustration which I've attached, it appears to be an equal-angle dial. It has a compass (label b)to allow N-S alignment of the dial. The shadow is cast by two vertical threads (label f). After some pondering, I have concluded that the sundial may be a form of magnetic azimuth dial, but this could well be wrong. My question is: would this dial work? best wishes, Peter -------------------------- Peter Mayer Politics Department The University of Adelaide, AUSTRALIA 5005 Ph : +61 8 8303 5606 Fax : +61 8 8303 3443 e-mail: [email protected] 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 ------------------------------------------------------------------------------ --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
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