OP DIALING. 343 



grees that II is distant from XII : and so, by making LECT. 

 15 degrees of the equator pass under the brazen me- ^-v^v 

 ridian for every hour, the first meridian of the globe 

 will cut the horizon in the distances of all the hours 

 from XII to VI, which is just 90 degrees ; and then you 

 need go no farther, for the distances of XI, X, IX, VIII, 

 VII, and VI, in the forenoon, are the same from XII, as 

 the distances of I, II, III, IV, V, and VI, in the after- 

 noon : and these hour-lines continued through the cen- 

 ter, will give the opposite hour-lines on the other half of 

 the dial : but no more of these lines need be drawn, 

 than what answer to the sun's continuance above the 

 horizon of your place on the longest day, which may be 

 easily found by the 26th problem of the foregoing Lec- 

 ture. 



Thus, to make a horizontal dial for the latitude of 

 London, which is 51J degrees north, elevate the north 

 pole of the globe 51J degrees above the north point of 

 the horizon, and then turn the globe, until the first me- 

 ridian (which is that of London on the English terres- 

 trial globe) cuts the north point of the horizon, and set 

 the hour-index to XII at noon. 



Then, turning the globe westward until the index 

 points successively to I, II, III, IV, V, and VI, in the 

 afternoon ; or until 15, 30, 45, 60, 75> and 90 degrees 

 of the equator pass under the brazen meridian, you will 

 find that the first meridian of the globe cuts the horizon 

 in the following numbers of degrees from the north 

 towards the east, viz. 11!, 24J, 38^,531, 71 A, and 90; 

 which are the respective distances of the above hours 

 from XII upon the plane of the horizon. 



To transfer these, and the rest of the hours, to a plale v - 

 horizontal plane, draw the parallel right lines ac and 

 bd upon that plane, as far from each other as is equal 

 to the intended thickness of the gnomon or stile of the 

 dial, and the space included between them will be the 

 meridian or twelve o'clock line on the dial. Cross this 



