We have now to consider “to what extent would a staircase rising at an angle of 31° 47′ towards the Sun, with a gnomon so placed at the top as to cast a shadow to the foot of the lower step on the shortest day of the year be affected by a movement in a perpendicular direction of the point of light to the extent of 23′, or ⅓ of a degree”? The effect would be widely different at different times of the year, being greatest at mid-winter when the shadows are longest, and least at mid-summer when the shadows are shortest. It follows from this that January 13 being a day but three weeks removed from mid-winter day the normal shadow would be not far from its longest possible length, and the effect of a displacement of 23′ would be neither more nor less than 1⁄12th of the whole range of the steps whatever that range might have been. This extent of motion, then, is fully sufficient to satisfy the condition prescribed by the Biblical narrative of there being such a deflection of the Sun’s light as would affect the shadow to the extent implied by the words “ten steps” or “ten degrees,” which is virtually the same idea. The same extent of motion could not have been produced under the same conditions either a few days earlier or a few days later; that may certainly be taken for granted. And the only point in which we are necessarily in doubt arises from the fact that we are ignorant of the actual number and nature of the graduations of Ahaz’s so-called “Dial.” If it were permissible to assume that there were 120 graduations on the instrument, be they steps properly so-called on a structure erected in the open air or be they lines on a flat surface on some instrument standing in a room, or what not, then the problem is solved, for 1⁄12 (as above) of 120 is ten—the “ten degrees” stated in the history.
As to whether the “dial” of Ahaz was a device built up of masonry in the open air or was an instrument for indoor use we know absolutely nothing, and speculation is useless. There is something to be said on both sides. Bosanquet, on abstract grounds, leans to the latter view; on the other hand he calls attention to the present existence in India, at Delhi and Benares, of ruined Hindoo observatories in the form of huge masonry sun-dials many yards in length and breadth and height.[33]
Finally it may be pointed out that there is some incidental confirmation to be found for this Hezekiah incident having happened in winter. That the season of the year was winter seems to be suggested by the word used in the original Hebrew in connection with the return of the shadow.
“Backward” in Isaiah xxxviii. 8 might also be translated, “From the end.” It would be very natural to hold that this implied that the motion of the shadow was upwards from the lower end of the group of steps towards which the shadow had gone down. Now the lower end of the steps could only have been the place of the shadow in December or January at or near the time of the winter solstice. Moreover the mention of the “lump of figs” seems to suggest the winter season. A cake of figs means dried figs, not newly gathered summer figs.
Putting all the facts together we may fairly conclude that the astronomical event which happened in connection with Hezekiah’s illness was an eclipse of the Sun, and that its date was January 11, 689 B.C.
A few other Scripture passages need a passing mention. In Isaiah xiii. 10 we read:—
“The Sun shall be darkened in his going forth, and the Moon shall not cause her light to shine.” It has been thought by Johnson that this passage is an allusion to an eclipse of the Sun, and so it might be; but on the other hand, it may be no more than one of those highly figurative phrases which abound in holy Scripture, and of which the well-known passage, “The stars in their courses fought against Sisera” (Judges v. 20), is a familiar example.
In Jeremiah x. 2 we read:—