azimuth dial
I am interested in a pedestal dial in the English Lake District. My interest is in the arrangement for finding the azimuth of the sun. The dial is by Richard Whitehead, dated 1688, and a central compass rose is divided into points, the points being further divided into one eighths i.e. better than 1.5 degrees. The gnomon is vertically drilled for a central shadow pin, which is missing. Does anyone have any information about shadow pins in sundials and are there other examples of dials centrally inscribed in points with the object of finding the sun's direction. And were points an essentially nautical feature? The dial was first listed in the BSS Sundial Register, No, in Cumbria, by Robert Sylvester. Frank 55N 1W -- Frank Evans [EMAIL PROTECTED] -
Re: azimuth dial
In answer to your question about the Whitehead dial of 1688 the shadow pin is missing but it must have been a round metal bar, doubtless of the same material as the dial, bronze and not a plumb-bob. The holes to receive this pin are obvious and at the cardinal, intercardinal and three letter points there are double lines on the dial plate to receive the thickness of the shadow pin. I am hoping to make a second visit to the dial fairly soon. The description held in BSS records and carefully written, presumably by Robert Sylvester reads: Octagonal dial of 45 cm. showing time from 4am to 8pm in half, quarter and eighth hours on scales inside the chapter ring and in minutes (with Arabic nos.) on outer edge. Strangely some of the actual hour lines on these inner scales seem missing [e.g. 6 and 7pm]. Inward (arrow with H form) and outward (line and dot form) half hour markers. Elaborate inner 32 point compass with all points named [e.g. SEbE] and on an adjacent (outer) scale with its reciprocal [e.g. NWbW] so as to give the sun's bearing. Compass designed to be used with vertical rod (not present) passed through holes in the gnomon and centred on the compass. Markers on either side of the main 32 points indicate the width of this shadow for accurate centring. Two scales further divide each of the 32 points into 1/4 and 1/8 intervals. A half division is provided outside these scales (to the inside of the dial) and marked by an inward line with a three dot arrowhead. Wonderful pierced gnomon with scroll pattern, the whole mounted on an excellent panelled octagonal stone pedestal which is slightly fluted and with no visible base. Design: Lat. 54deg 40'N. Dear Frank, I was intrigued by the description of the Richard Whitehead dial in the BSS Register so I'm glad that you are investigating it. Whitehead was apprenticed to my hero Henry Wynne, who's large double horizontal dials feature azimuth scales. The one at Wrest Park (Bedfordshire) has an azimuth scale divided down to one-eighth points, as well as to quarter degrees. The points are labelled, for example, SWbS. Slightly later dials of similar size (about 750mm diameter) by Wynne seem to make do with quarter points and half degrees. Most of the other information on the dials is astronomical, rather than nautical. By coincidence, I am currently designing a dial for an Americal client which will include a central pin to show the azimuth of the sun, particularly at sunrise/sunset. In this case, the gnomon will be of the cantelevered or underslung type where the shadow is cast by the bottom edge of the gnomon. This leaves the centre of the dialplate clear for the scales. I would be interested to see how Whitehead arranged his shadow pin for the azimuth scale. Do you think it was an actual pin rather than a plumb-bob or plummet? Regards, John Frank 55N 1W -- Frank Evans [EMAIL PROTECTED] -
Re: azimuth dial
I was intrigued by the description of the Richard Whitehead dial in the BSS Register so I'm glad that you are investigating it. Whitehead was apprenticed to my hero Henry Wynne, who's large double horizontal dials feature azimuth scales. The one at Wrest Park (Bedfordshire) has an azimuth scale divided down to one-eighth points, as well as to quarter degrees. The points are labelled, for example, SWbS. Slightly later dials of similar size (about 750mm diameter) by Wynne seem to make do with quarter points and half degrees. Most of the other information on the dials is astronomical, rather than nautical. By coincidence, I am currently designing a dial for an Americal client which will include a central pin to show the azimuth of the sun, particularly at sunrise/sunset. In this case, the gnomon will be of the cantelevered or underslung type where the shadow is cast by the bottom edge of the gnomon. This leaves the centre of the dialplate clear for the scales. I would be interested to see how Whitehead arranged his shadow pin for the azimuth scale. Do you think it was an actual pin rather than a plumb-bob or plummet? Regards, John -Frank Evans <[EMAIL PROTECTED]> wrote: Greetings Fellow Dialists,I am interested in a pedestal dial in the English Lake District. My interest is in the arrangement for finding the azimuth of the sun. The dial is by Richard Whitehead, dated 1688, and a central compass rose is divided into points, the points being further divided into one eighths i.e. better than 1.5 degrees. The gnomon is vertically drilled for a central shadow pin, which is missing.Does anyone have any information about shadow pins in sundials and are there other examples of dials centrally inscribed in points with the object of finding the sun's direction. And were points an essentially nautical feature?The dial was first listed in the BSS Sundial Register, No, in Cumbria, by Robert Sylvester.Frank 55N 1W-- Frank Evans[EMAIL PROTECTED]-Dr J R DavisFlowton DialsN52d 08m: E1d 05m
MEAN TIME AZIMUTH DIAL
Hello All, For some time now I have been working on a mean-time dial using the suns azimuth. I have made a quarter scale model and have posted some images and a description on my website www.sun-dials.net. If you go to WHAT'S NEW there is a link to AZIMUTH DIAL at the foot of the page. If an organisation would be interested in such a dial I would willingly give my design services free. Silas Higgon.
