It is a difficult matter to fix the date either of the _De eodem et diverso_ or of the _Questiones naturales_, and to account satisfactorily for the various allusions to contemporary events and to Adelard’s own movements which occur in either. It is not even entirely certain which treatise was written first, as neither contains an unmistakable allusion to the other. On general grounds the _De eodem et diverso_ would certainly seem the earlier work, but there are some reasons for thinking the contrary. It seems clear that not many years elapsed between the composition of the two works, but how many is uncertain. It is evident that the _De eodem et diverso_ must have been written by 1116 at the latest in order to dedicate it to William, bishop of Syracuse. But the _Questiones naturales_ apparently might have been dedicated to Richard, bishop of Bayeux, at almost any time during his pontificate from 1107 to 1133, although probably not long after 1116. [Sidenote: Before what queen did Adelard play the _cithara_?] Professor Haskins would narrow down the time during which the _De eodem et diverso_ could have been written to the years from about 1104 to 1109, with the single year 1116 as a further possibility. He says, “Adelard speaks of having played the _cithara_ before the queen in the course of his musical studies in France the preceding year, and as there was no queen of France between the death of Philip I and the marriage of Louis VI in 1115, the treatise, unless the bishop of Syracuse was still alive in 1116, would not be later than 1109.”[104] But may not the queen referred to have been Matilda, the wife of Henry I?[105] She was a patroness both of artists and of men of letters, and the Pipe Roll for 1130 and the treatise on the astrolabe have shown us that later, at least, it was the English royal family with which Adelard, himself an Englishman, was connected. It is of “Gaul,” not of “France” in the sense of territory subject to the French monarch, that Adelard writes,[106] and Normandy was of course under Henry’s rule after the battle of Tinchebrai in 1106. [Sidenote: Circumstances under which the _De eodem et diverso_ was written.]