Now, Chaucer, whose choice of expression on scientific subjects is often singularly exact, says, "Our hoste _saw_ that the sonne," &c.; he must therefore have been referring to some visible situation: because, afterwards, when the time of day has been obtained from calculation, the phrase changes to "_gan conclude_" that it was ten of the clock. It seems, therefore, certain that, even setting aside the question of consistency between (1.) and (2.), we must, _upon other grounds_, assume that Chaucer had some meaning in the expression "arke of the artificial day," different from what must be admitted to be its obvious and received signification. To what other ark, then, could he have been alluding, if not to the _horary_ diurnal ark? I think, to the AZIMUTHAL ARCH OF THE HORIZON included between the point of sunrise and that of sunset! The situation of any point in that arch is called its bearing; it is estimated by reference to the points of the compass; it is therefore _visually_ ascertainable: and it requires no previous knowledge of the hour in order to determine when the sun has completed the fourth, or any other, portion of it. Here, then, is _prima facie_ probability established in favour of this interpretation. And if, upon examination, we find that it also clears away the discrepancy between (1.) and (2.), probability becomes certainty. Assuming, upon evidence which I shall hereafter explain, that the sun's declination, on the day of the journey, was 13 deg. 26' North, or thirteen degrees and half,--the sun's bearing at rising, in the neighbourhood of London, would be E.N.E., at setting W.N.W.; the whole included arch, 224 deg.; and the time at which the sun would complete one-fourth, or have the bearing, S.E. by E., would be about 20 minutes past nine A.M.,--thus leaving 40 minutes to represent Chaucer's "halfe an hour and more!" A very remarkable approximation--which converts a statement apparently contradictory, into a strong confirmation of the deduction to be obtained from the other physical facts grouped together by Chaucer with such extraordinary skill! On the other hand, it is impossible to deny that the "hoste's" subsequent admonition to the pilgrims to make the best use of their time, warning them that "the fourthe partie of this day is gon," seems again to favour the idea that it is the day's actual horary duration that is alluded to. This can be only hypothetically accounted for by observing that in this, as in many other instances, Chaucer seems to delight in a sort of disguised phraseology; as though to veil his true meaning, and designedly to create scientific puzzles to exercise the knowledge and discernment of his readers. A. E. B. Leeds, April 14. 1851. * * * * * FOREIGN ENGLISH--GUIDE TO AMSTERDAM.