I noticed that one of the write ups for sundial stated that the item would be no use at night time, although this is not strictly true.

With a table of suitably calculated numbers (dependent on latitude), the time read on the dial from its shadow cast from the moon can then be used to estimate the time of night: look for the day of the lunar month in the upper table of numbers, and then add the number below it to the time you have just read (in hours).

Unfortunately moondials are most accurate when they are of least utility - when there is a new moon.

Moon dials are quite rare - the only one I know of is in the Old Court of Queens' College, Cambridge. It's reasonably accurate, but can only be read when the moon is shining brightly, as the lights from inside the court obscure the shadow.

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