from the LRB archive lovely 1979 William Empson on Fairy Flight in ‘A Midsummer Night’s Dream’

"The distance to the Moon is about 60 times the radius of the Earth, as was already known in Classical times, and the Moon goes round the Earth in about 30 days, so the speed of the middle of the Moon’s sphere, the part which carries the Moon, is about twice the speed of the equator, which revolves in a day. So the working fairy does at least half a mile a second, probably two-thirds, and the cruising royalties can in effect go as fast as her, if they need to. Puck claims to go at five miles a second, perhaps seven times what the working fairy does. This seems a working social arrangement. But if all the stars go round the Earth every day, with the Moon and planets lagging only slightly behind, the speed of the Moon’s sphere is about 60 times the speed of Oberon when he remains in the dawn, and the working fairy is going very much faster than the boast of Puck. I agree that the phrases are meant to sound rather mysterious – probably Shakespeare asked the advice of Hariot, who was certainly a friend of Marlowe – but they would not be meant to be sheer nonsense, as has for so long been assumed..."