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of Campanus’ work on the Compotus: a medieval science focused on calculating the calendar and the dates of Christian feasts to our printed text. These correspondences are a new proof of the fame of Bacon during his lifetime.

One aspect of Bacon’s criticism on the teaching of mathematics (pages 118, 121), that too much time is wasted on unnecessary demonstrations, will be more generally appreciated at the present date than some other of his strictures. He would seem to think that a student needs only to know the actual results, except in a few cases where it is necessary to see how these can be proved to be true.

His criticism of the validity of certain of Euclid’s assumptions and definitions which need demonstration (page 119) is very much in line with the thought of modern editors. It is not entirely original: a great deal of early criticism is summed up in the work of Anaritius, also known as al-Nayrizi, was a tenth century Persian mathematician and astronomer who wrote influential commentaries on Euclid. Anaritius (Al Narizi), and Bacon’s additions or elaborations have not been carefully distinguished. His main contributions seem to be concerned with Book V, the study of ratios and proportions, which was his principal interest in the study of Mathematics as applied to life. His selection of the propositions in Euclid of chief importance is illuminating (pages 140 to 143); they run mainly from the sixth to the eighth book.

One of the interesting points in the bibliography of the subject is his mention of the ‘special edition’ original: "editio specialis" of Adhelard. I take these words to mean ‘a setting forth in particular’, and was disposed to think they applied to the prologue of the Digby manuscript 174, folio 99, especially as three of the quotations are found there textually. The question is still open until a serious study of his Euclid manuscripts is undertaken.

A further volume of this series will (God willing original: "Deo volente") complete the issue of unpublished recognized works of Roger Bacon. It should consist of short tracts, of the unpublished parts of two long treatises which overlap sections of the Communia Naturalia: Common Principles of Nature, one of Bacon's primary works on physical science, attempts to identify the scattered fragments original: "disjecta membra" of the ‘My Metaphysics’ original: "Metaphysica mea", and an edition of the On the Power original: "De Potestate" to get rid of the well-known enigma ‘Luru vopo vir can vtriet’. This famous anagram is often discussed as a hidden formula for gunpowder or a secret alchemical recipe. (See Nature, February 11, 1928.)