An obelisk was the simplest, though an imperfect form of Heliotropion, marking indistinctly the length of a shadow at different times of the year, especially the extremes of length and shortness at mid-winter and mid-summer. It is perhaps interesting to mention that travellers have recorded, in various places, various devices for furnishing information respecting these matters. For instance, in Milan Cathedral the meridian line is marked on the pavement, and along this line, an image of the Sun coming through an aperture in the southern wall travels backwards and forwards during the year according to the seasons. Some Jesuit missionaries who visited China about the middle of the last century, noticed a device of this character in operation at the Observatory at Pekin. A gnomon had been set up in a low room and one of the missionaries, M. Le Comte, describes in the following words what they saw in connection with this gnomon:—“The aperture through which the rays of the Sun came was about 8 ft. above the floor; it is horizontal and formed of two pieces of copper, which may be turned so as to be farther from, or closer to, each other to enlarge or contract the aperture. Lower was a table with a brass plate in the middle on which was traced a meridian line 15 ft. long, divided by transverse lines which are neither finished nor exact. All round the table there are small channels to receive the water, whereby it is to be levelled.”[32] All this may seem rather a digression, and so it is, but I am following Mr. Bosanquet herein in order the better to justify the argument that it was an eclipse of the Sun which marked the important incident in Hezekiah’s life which has been handed down to us by the sacred writer. It is evident that if a flight of steps were erected on the principles which were set forth above, the steps sloping upwards and southwards (for the Northern Hemisphere) from the lowest step to within a few inches below an aperture in the gnomon suitably arranged, the ray or image of the Sun, whichever it was, would travel day by day up and down such steps between solstice and solstice. We may conclude, therefore, that the instrument which Hezekiah gazed at, and which is called in Scripture, the “Dial” of Ahaz, was what the Greeks would have termed a Heliotropion.