"Professor Burnet says, 'the Cowthorpe Oak is sixteen hundred years old. We may ask, how is this ascertained? From tradition, or calculated on botanical data? If the latter, it is possibly far removed from truth. The method of calculating the age of dicotyledonous trees, with _hollow trunks_' [and he elsewhere says, so large is the hollow of the Cowthorpe Oak, that it is reported to have had upwards of seventy persons at one time therein assembled], 'is by multiplying the number of rings comprised in a given portion of the remaining wood, by the proportion which half the entire diameter of the trunk bears to the selected portion.... It is evident, however, that this calculation proceeds on the assumption of two circumstances, whose probable variations may seriously affect the result. "'1st. That all the rings are of equal width. "'2nd. That each ring is of uniform width on both sides of the tree. "'It is known that the width of the rings diminishes with the age of the tree, until, at the latter part of its life, they are of very inconsiderable width, compared with those near the centre of the trunk.... Again, it is also known that the width of the rings differs according to season, being of course wider in those seasons most favourable to the action of the leaves, and the general processes of growth; but greatly diminished in seasons affected by blight, cold, or other causes of injury to the leaves. It also happens that the rings are often of unequal width on opposite sides of the trunk.... While, if the tree be so hollow as to have no portion of its centre remaining ... will expose the calculation to ... error. In reference, therefore, to the Cowthorpe Oak, we abandon all scientific pretension.'" The foregoing is extracted from an account of the Cowthorpe Oak by C. Empson, Esq., 1842: Ackerman, Strand. COKELY. "_Mirabilis Liber_" (Vol. iv., p. 474.).--I have a copy of this book, from which a "prophecy" is quoted in "N. & Q." p. 474., but the translation there given differs from the prophecy, as given in my book. I have therefore copied it out _at length_, and exactly as given in the original, with all the faults of barbarous Latin and want of stops. My book is a small 8vo. without date: the first part in Latin, and the second in French, in Gothic characters. The colophon runs thus: "On les vend au roy David en la rue St. Jacques."[5] [Footnote 5: [For a notice of the various editions of this work, see Brunet, _Manuel du Libraire_, _s. v._ Mirabilis, tome iii. p. 401.--ED.]] The "prophet" is _S. Severus_ not _S. Cæsario_. "PROPHETIA SANCTI SEVERI ARCHIEPISCOPI.