Now one would think that Tyrwhitt, when he found his author relating facts, "seemingly intended to be so accurate," would have endeavoured to discover whether there might not be some hidden meaning in them, the explaining of which might make that consistent, which, at first, was apparently the reverse.
Had he investigated with such a spirit, he must have discovered that the expression "arke of the artificial day" could not, in this instance, receive its obvious and usual meaning, of the horary duration from sunrise to sunset—
And for this simple reason: That such a meaning would presuppose a knowledge of the hour—of the very thing in request—and which was about
to be discovered by "our hoste," who "toke his wit" from the sun's altitude for the purpose! But he knew already that the fourth part of the day IN TIME had elapsed, he must necessarily have also known what that time was, without the necessity of calculating it!
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 primâ 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.