One form of a Sun-dial, and the one most familiar to us. is 

 constructed as a right-angel triangle of metal or masonry, called 

 a gnomon, a Greek word meaning an instructor or one that indi- 

 cates, with the hypothenuse, called the rod or style, pointing to 

 the North and parallel with the earth's axis — that is, its plane 

 coincides with the meridian ; and this, with a fixed surface, which 

 may be the base upon which it stands, or a semi-circle — a quad- 

 rant upon each side — passing through its center and traced with 

 lines indicating the hours and minutes and upon which falls the 

 shadow of the style, is called a Sun-dial. 



Giovanni Florio, an Englishman of Italian parentage, a Pro- 

 fessor of Oxford University and a personal friend of Shakespeare, 

 in one of his books published about 1598, describes the gnomon 

 as "the know-man or gnow-man of a diall, the shadow whereof 

 pointeth out the howers." 



The figure may make the description clear, viz : 



The hypothenuse or style SN is directed from South to North. 

 SE is the surface of the Earth and NSE stands upon the meridian 

 of the place where the dial is constructed. The latitude of the 

 place is the angle at S, subtended at the center of the Earth by 

 an arc of the meridian between the zenith and the celestial equa- 

 tor. Latitude is always equal to the altitude of the celestial pole. 



An excellent representation of the Sun-dial at Delhi is pre- 

 sented by the annexed half-tone copy of an engraving I obtained 

 in that city. 



In the Hindu or Urdu language it is called the Brahat-Sum- 

 rat, the big Sun-dial, and Sumrat-Yantra, the Prince of Dials. It 

 is constructed of brick masonry, its base being 104 feet long, the 

 hypothenuse or style is 118 feet and 7 inches in length and the 

 perpendicular is 56 feet and 7 inches from its base to the apex. 

 The gnomon has steps in the center affording an easy ascent to 

 the top, where stands a low circular tower upon which is a small 

 modern Sun-dial of steel. 



On each side, a masonry quadrant of a circle is built at a 

 distance of 49 feet and 4 inches from the center of the gnomon. 

 These quadrants pass under the base of the gnomon, which at 



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