Isobel is in a sunny disposition this week:

In a week in April with snow and several hard frosts, now finally we have a bit of sunshine with some warmth in it. This prompted me to have a look at sundials, at home and abroad.

The Park by Frank McKelvey. Oil. B1895. Funduklian Collection. BMAG

The part of the dial which casts the shadow is called a gnomon. In the northern hemisphere it is usually orientated so that it points northward and is parallel to the rotational axis of the Earth.

There are seven types of sundials – horizontal, vertical, portable, equatorial, polar, analemmatic and reflected ceiling dials.

The world’s largest sundial is the Samrat Yantra (which translates as Supreme Instrument). It is located at the Jaipur observatory in Rajasthan, India. Built in the 18th century, it is 90 feet tall.

The oldest known sundial was found in Egypt and dates from around 1500BCE. It was used to measure work hours.

Photograph from the collection of Dr J. W. Jackson

The dial at St Lawrence church at Eyam is vertical and is above the priest’s door. Built in 1775 by a local stone mason, thought to be William Shaw, it shows time in half hours, the signs of the zodiac and times in other cities around the world.

The dial at St Peter’s in Hope is a horizontal dial, mounted on pillar which stands on a base of five octagonal steps.

The museum has a pocket sundial in its collection. Dating from the 18th century, it was found in Pooles Cavern in Buxton and may well have been dropped by a visitor at a time when tours were done by crawling along, and unscrupulous guides threatened to leave visitors in darkness unless further money was paid to them! Here, the gnomon flips up when in use and folds flat when being carried.