How to position a sundial

* Read our previous article on the history of sundials

Post-obit on from terminal calendar week's commodity on the history of sundials, this calendar week nosotros tell yous how to install and position a horizontal sundial correctly.

Sundials are scientific instruments which can tell the time with precision if they are well-made and gear up up accurately. This is relatively simple as long as you pay attention to the finer details.

Your sundial needs to be placed on a plinth which is horizontal, preferably in an surface area that sees the sun and it must be oriented towards the true North, which is very shut to the Pole Star.

Cull your location carefully. If your site has trees or buildings near to it you should effort to organise the sundial and so that the view to the Westward is equally open up as possible, because most people will be inspecting the sundial in the late afternoon.

If you have trees or buildings to the Southward that will not be and then of import as the lord's day volition not be so high in the sky at the center of the twenty-four hour period.

There are 4 ways to find due N:-

1)   Traditional – using a pole in basis
2)   A Compass
three)   The website to observe solar due north
4)   Or the new sundial app.

ane. The traditional way of finding truthful North is to put a pole in the ground, make sure it is accurately vertical with a plumb line or spirit level on ii sides at right angles, and so describe circles on the footing from the base of the pole. On a sunny day, note the position where the shadow of the tip of the pole just touches one of the circles in the morning, and again in the afternoon. Bisect this angle, and that will give you an accurate North-S or meridian line.

2. Some other way is to utilise a compass, but this is not recommended considering the length of the needle is very brusk, and anyway it points to magnetic Due north, and many people find the correction to true North difficult to apply.

3. Modernistic technology has given us ii new ways to find truthful North. If you know the exact fourth dimension of solar apex, and you lot rotate your sundial till the shadow falls on 12, it will be pointing to truthful North. There is a very useful website, www.solar-noon.com, which will tell you the exact fourth dimension of solar noon wherever you lot are in the world. The picture shows the printout for the first few days of each month for Windsor Castle.


4. An innovation this year is SNAP – the sundial app which shows you lot, for several k cities worldwide, the sunday time and clock time at that location, with a picture of a sundial face and the shadow on it.  If you lot can find a city on the aforementioned longitude as yous are, you can prepare your sundial to the lord's day time shown whatever time of day it is. And if the longitude is not quite right for you, you can just add 4 minutes for every whole caste, or 4 seconds for each 2nd of longitude, if you are due w of your called urban center, or subtract if you are due east of it.

Accurateness depends on the way they're made. Information technology is possible to read a scientific sundial to within a couple of minutes, although some sundials will be less authentic.

What do yous do when the clocks change? Aught. The position of true Northward does non alter simply because of an act of Parliament! You conform your mind, not the sundial. And just call back to add ane 60 minutes in the summer.

Piers Nicholson runs a leading sundial information website world wide web.sundials.co.uk and has also designed an innovative range of spot-on sundials in brass and stainless steel; the range includes horizontal, polar, and equatorial sundials.

This is an commodity from ProjectBook which provides a wide range of data for the conservation, restoration, care and repair of menstruum and listed buildings. spot-on sundials are members of ProjectBook's Products Directory which provides a showcase for specialist products, suitable for use on traditional properties. Updated daily with new content, the website features the Heritage Annals, a products directory, informative articles, current news, events and more than. For more information, visit www.projectbook.co.great britain.

www.solar-noon.com
SNAP – the sundial app