The Sundial at All Saints' Church in Isleworth
The dial at this church was recently removed for restoration. The restoration has been carried out by Royal Warrant holders Charles Perry Restorations of St Albans. The dial has been repainted and even repositioned a few times over the years and was in a very dilapidated condition when it was taken down this time. See some pictures of it in the good times and the bad here...
The first dial was originally erected to the memory of Susannah, wife of Colonel Sir Nicholas Lawes who had been Governor of Jamaica from 1718 to 1722. Her father, Thomas Temple, is said to have given Lawes his Temple Hall Estate in Jamaica, as a dowry on their marriage in 1698. Nicholas is credited with introducing coffee growing (Blue Mountain Coffee, no less) into the island in the 1720s and with setting up the first printing press in Jamaica. The city/place arcs refer to solar time in Jamaica, Jerusalem and Moscow. The linkages with Jerusalem and more particularly, with Moscow are not understood. It was common to include Jerusalem in any set of significant city marking on dials at that time. However why Moscow should be important to this family isn't clear. Perhaps Lawes had military connexions there. As far as the dial is concerned, this would then represent a balance of interests of husband and wife.
There were oddities with the hour markings of these place name arcs and with the direction stated for the one for Jamaica. The central scale was intended to show lines of the sun's altitude but these were incorrectly drawn and there doesn't ever appear to have been a nodus whose shadow against this scale would have indicated the sun's altitude at any time. Finally, the hour lines did not all point to a common origin and the gnomon was bent and was even wrongly positioned too. As if all that was not enough the declination of the dial in its present place was not accurately known. With its present mounting high up between two modern, angled brick pillars, simple methods of declination measurement did not apply. Then there was the state of the wooden backing and the missing Western-most mahogany corbel. It was necessary to correct the various errors in delineation and positioning and to effect a remounting using as much original material as possible and then do a repaint which would stand the ravages of time for many years. There was a lot to do!
Here are some images relating to the restoration of this dial.
Hover over any image for a description; Click on any image for a larger picture.
Photos 3&4 courtesy of Maxwell Hamilton
under a Creative Commons Licence. Photo 1 courtesy of Gillian Churchill
Photo 2 courtesy of Charles Perry Restorations. Others © P.Powers 2013
Some known problems with the existing dial.
1. Some of the hour lines are incorrectly drawn. They appear to have incorrect angles for the dial’s current location and position which, though this needs confirmation, appears to face about 5.5 degrees East of South. Notably the angles of the hour lines around 6am and 5pm appear from trial calculations to be somewhat too steep. The hour lines do not extend through the dial's origin as they should and that origin is actually just off the dialplate.
2. The subdivisions below the half hours have simply been ‘sketched’ in at angles that do not ‘point’ to the origin of the dial as they should. Moreover the subdivisions have been drawn are at 6 minute intervals – something which is not present on any other English dial as far as is known.
3. The hour and half hour lines have an unusual appearance even though there is some consistency. The hour lines have no ending and seem too long and the half hour lines have prominent endings (a cross) and seem too short in places.
4. The half-sun motif is strangely placed below the dial origin. This may well be intentional, given the need for the banner motto above it, but it is unusual. More commonly the origin of the dial (otherwise called the root of the gnomon) would be at the centre of any representation of the sun.
5. The gnomon has been wrongly located along the noon line of the dial. For the direction that the dial is currently assumed to face, it should lie at an angle to the West of 4.63°, that is to say along the (corrected) hour line for 11:32am.
6. The gnomon has become detached from its upper fixing.
7. Gnomons of large dials frequently incorporate a drip feature to redirect falling rainwater away from its fixing to the dial plate and thus reduce dial plate staining. There doesn’t seem to have been any particular attempt at that in the present dial (for example with the provision of a small, though imperceptible, downward slope of the under-gnomon piercing) though the long gnomon certainly helps.
8. There are other scales on the dial yet there is apparently no nodus nor any provision for one, to act as an indicator against them.
9. The inner part of the dial holds a scale against which the shadow of a suitably placed nodus would indicate the altitude of the sun. These so-called almucantar lines are currently wrongly drawn, many of them appear to be approximate circular arcs, when they should be hyperbolae and, improperly, they seem to align vertically with the hour scale. They should be centred on the position of a perpendicular dropped from the nodus to the dialplate; that is to say be centred slightly offset from the noon line because of the required small twist of the gnomon to the West.
10. The sole presence on a dial of almucantar lines is most unusual, possibly even unique in Britain. Such lines only tend to be included when they are in the presence of other dial 'furniture'. The very lowest of these lines is in fact a line marking (or intended to mark) the summer solstice. The shadow of the nodus would travel along this line at the date of the solstice. There are however no other lines of the sun’s declination, such as for the winter solstice or the equinoxes. These may have been lost in an earlier repaint; replacement of perhaps the main three of them would make the dial more in keeping with its peers.
11. There is no identification on the dial of what the lines of altitude actually are. Now this is by no means unusual in itself but the presence of altitude lines on a dial is so unusual that some identification (perhaps the latin ‘Altitudo’) might serve. This could be arranged vertically on one side of the rectangle where it would then remove the need to double mark each end of the lines with numerals.
12. The dial also includes the solar hour numerals at three other places on the earth: Jamaica, Jerusalem and Moscow. They serve to give an approximate indication of the solar time at these places from the current position of the gnomon’s shadow. These place times should be calculated from the solar time at these locations relative to that at Isleworth and not by using modern time zones.
13. The rhumb line direction of these places from Isleworth (they are also called loxodromic lines*) is given using 32 point compass notation. That for Jamaica is incorrect - probably from a repainting omission.
14. It isn’t clear why the time indications for Moscow should be in Roman numerals and those for Jamaica and Jerusalem be in Arabic ones. There might be some historical or family reason for distinguishing the first two places from the last. However, if there isn’t any such reason and it looks like a mistake it might be more consistent to repaint using Arabic numerals for all three place scales.
15. The moulding around the actual dial plate exists on three sides only; balancing this should be considered as a part of the restoration process.
16. In the past the dial has been repainted in several different colour schemes and one or other might well have been that used on the original dial. If that is known then it may well be appropriate to use that scheme. However in the absence of any such information it might be better to fall back to traditional schemes of the period: black, blue, red, white, gold and green.
Latest News. As of the end of April 2013, restoration was proceeding. Instead of preparing a 'copy' of the previous dial, reference was made to the many images of earlier versions and along with an accurate redrawing of the dial lines a careful restoration to an earlier design has been achieved. The new backing for the dial was made using two layers of very thick marine ply, a new corbel and various wooden mouldings were carved out of mahogany and older parts of the dial that could be recovered were repaired with dovetailed inserts of good wood. The calculations for the 'dial furniture' - the hour, declination and altitude lines as well as the times in the three places had also been completed. A full sized CAD drawing of the dialplate had been prepared for use as a 'cartoon' by the signwriter who was to paint the dialplate as well as the scrolled surround. A first draft of that cartoon can be seen by clicking on the thumbnail at the left. It does not include all artwork of course since all that was to be drawn in the correct place by the signwriter using fonts appropriate to the original age of the dial. As a result text and numerals are merely indicators on a plot of this sort. As of May 2013 painting was complete and the dial was scheduled to be reinstalled at the church on Saturday 25th May 2013 - in good time for a celebratory church event at the beginning of June. An image of the completed dial in the workshop (slightly perspective-adjusted since its huge size made indoor photography particularly difficult!) is included in the selection above.
As of the beginning of June 2013, the dial has been installed and is close to being correctly aligned. The earlier dial was actually (and wrongly!) mounted so as to recline slightly and with the current fittings the restored dial also wrongly reclines slightly. Possible correction of this will be considered in the coming period.
* Rhumb or loxodromic lines are the lines on which a ship sails when her course is set to be always in the direction of one and the same point of the compass. These are straight lines on a Mercator projection.
Comments and any historical information about the Isleworth dial and its restoration are welcomed. Please send any comments to the Webmaster.
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