Dial; Sun-Dial

Concise Bible Dictionary:

Some contrivance, not definitely specified, by which the divisions of the day were ascertained by the shadow of some gnomon or pillar, caused by the sun falling upon a series of steps or degrees (2 Kings 20:8-118And Hezekiah said unto Isaiah, What shall be the sign that the Lord will heal me, and that I shall go up into the house of the Lord the third day? 9And Isaiah said, This sign shalt thou have of the Lord, that the Lord will do the thing that he hath spoken: shall the shadow go forward ten degrees, or go back ten degrees? 10And Hezekiah answered, It is a light thing for the shadow to go down ten degrees: nay, but let the shadow return backward ten degrees. 11And Isaiah the prophet cried unto the Lord: and he brought the shadow ten degrees backward, by which it had gone down in the dial of Ahaz. (2 Kings 20:8‑11) and Isa. 38:88Behold, I will bring again the shadow of the degrees, which is gone down in the sun dial of Ahaz, ten degrees backward. So the sun returned ten degrees, by which degrees it was gone down. (Isaiah 38:8)). Hezekiah asked that the shadow might go backward ten degrees, and this took place on the dial of Ahaz. The same thing may not have occurred elsewhere, as it was simply to strengthen the faith of Hezekiah, nor is it necessary to suppose that the motion of the earth was reversed. May not the phenomenon have been produced by a peculiar state of the atmosphere causing refraction of the light passing through it? In whatever way it was brought about, it was by the power of God. Apparently a report of it reached Babylon, and ambassadors from the princes were sent to inquire of the “wonder” that had occurred (2 Chron. 32:3131Howbeit in the business of the ambassadors of the princes of Babylon, who sent unto him to inquire of the wonder that was done in the land, God left him, to try him, that he might know all that was in his heart. (2 Chronicles 32:31)).
 
Modern Sundial