Produced by Marius Masi, Don Kretz and the Online Distributed Proofreading Team at http://www.pgdp.net Transcriber's notes: (1) Numbers following letters (without space) like C2 were originally printed in subscript. Letter subscripts are preceded by an underscore, like C_n. (2) Characters following a carat (^) were printed in superscript. (3) Side-notes were relocated to function as titles of their respective paragraphs. (4) Macrons and breves above letters and dots below letters were not inserted. (5) [root] stands for the root symbol; [alpha], [beta], etc. for greek letters. (6) The following typographical errors have been corrected: ARTICLE GEOFFREY: "... his history in chiefly one of quarrels, with the see of Canterbury, with the chancellor William Longchamp, with his half-brothers Richard and John, and especially with his canons at York." 'William' amended from 'Willian'. ARTICLE GEOLOGY: "... and at the same time greater appreciation has been shown of the signification and strength of the geological proofs of the high antiquity of our planet." 'strength' amended from 'stength'. ARTICLE GEOLOGY: "... it can be demonstrated that sometimes an inch or two of sediment might, on certain horizons, represent the deposit of an enormously longer period than a hundred or a thousand times the same amount of sediment on other horizons." 'might' amended from 'much'. ARTICLE GEOLOGY: "But no such extensive disturbance of the normal conditions of the distribution of life can take place without carrying with it many secondary effects, and setting in motion a wide cycle of change and of reaction in the animal and vegetable kingdoms." 'kingdoms' amended from 'kindgoms'. ARTICLE GEOMETRY: "The bases and altitudes of equal solid parallelepipeds are reciprocally proportional; and if the bases and altitudes be reciprocally proportional, the solid parallelepipeds are equal." 'are' amended from 'and'. ARTICLE GEOMETRY: "An alternative method of testing a relation is illustrated in the following example:--If A, B, C, D, E, F be six collinear points, then" 'following example:--' amended from 'example: following'. ARTICLE GEOMETRY: "3. In an hyperbolic involution any two conjugate points are harmonic conjugates with regard to the two foci." 'an' amended from 'a'. ARTICLE GEOMETRY: "If two lines, given by their projections, intersect, the intersection of their planes and the intersection of their elevations must lie in a line perpendicular to the axis, because they must be the projections of the point common to the two lines." 'planes' amended from 'plans'. ARTICLE GEOMETRY: "Where this is the case, if [alpha] be the measure of curvature, the linear element can be put into the form" 'if' amended from 'it'.