Perhaps the best place to begin an understanding of how sundials work would be to imagine a pictorial view of the Earth at the North Pole In this diagram it is the Sun which seems to move at 15° every hour. The shadow-casting element of a sundial is usually called the 'gnomon' of which the edges are its 'styles'.

The reasons why you have to make adjustments to convert the time shown by the sundial into that shown by a clock. Part 4 Essential considerations when designing a sundial.

How sundials work. Everything you need to know about how and why sundials work.

See the diagram below for the main technical terms for the parts of the sundial. The triangular part is the 'gnomon', which points North (or South in the Southern hemisphere). The edge of the gnomon - that part which makes the shadow - is called the 'style'. Unless your gnomon is very thin, you will have two styles, one on each side.

Perhaps the best place to begin an understanding of how sundials work would be to imagine a pictorial view of the Earth at the North Pole In this diagram it is the Sun which seems to move at 15° every hour. The shadow-casting element of a sundial is usually called the ‘gnomon’ of which the edges are its ‘styles’.

A vertical sundial on a truly south-facing East/West wall has a central vertical noon line and a symmetrical arrangement of hour lines. The hours will begin at 6am and end at 6pm. Sundials on walls lying at an angle to truly East/West are said to 'decline'. In most cases the noon line will still be vertical but the gnomon

2016年5月15日 · 2. Distance between shadows cast by gnomon at equal time intervals. (Which is what a sundial uses to measure time of day.) The sundial at the south pole seems to marking out equidistant distances at each hour - #2. And it is a full circle. Which would be a more or less close match to flat earth northern "hemisphere - inside the sun's orbit.

A way this is often shown is as an 'Equation of Time' graph like this. You read along the month scale at the bottom and find the current date, then look up to see how many minutes to add or subtract. Often this graph will be included on the sundial.

The British Sundial Society. The British Sundial Society takes an interest in all aspects of telling the time by the sun. The history, the art, the science and the making of sundials. Members receive a quarterly publication with articles on all aspects of sundials.

Another alternative is to work out what time the dial should be showing and align it so that it does tell that time - which does require a sunny day. This method assumes that your sundial has been made with the correct angles, but if you come back to it a few hours later and the time is still accurate, you can have confidence that it is ...