The sphere of Apuleius from f.53v of MS B.15(I), a medical miscellany (English, 14th-15th century). An accompanying text explains how the sphere was to be used to predict whether a patient would live or die. The letters of the patient’s name were first to be assigned numbers according to the scheme written in the outer ring of the sphere. To this was to be added a number for the day of the week on which the patient fell ill, calculated according to the text at the four corners of the sphere. Following further addition and division the doctor would arrive at a number between 1 and 30, which he would then find in the row of numbers running down the centre of the sphere. A number in the top half of the sphere, labelled vita, indicated life, while a number in the bottom half, labelled mors, portended death.