D I A 



Exs. What number of degrees, minutes, &c, in the English seal* cor 

 espond to 71. 15'., and to 2C 3 . 0735, in the French scale. 



26.0735 

 2.G07S5 



3.48615 

 60 



27.96900 



58.14000 Answer 23. 27'. 



DEW. See Rain. 

 DIALLING. 



In all Dials universally, the style or gnomon is parallel to the earth's 

 axis, and, on account of the great distance of the sun, may be imagined 

 actually to coincide with it. In like manner the dial plate is parallel to, 

 and supposed actually to coincide with, some great circle of the earth j 

 and the hours may be conceived to be traced out by the shadow of the 

 axis of the earth (here supposed hollow) upon one of these great circles. 

 Hence there may be an infinite number of different kinds of dials, as 

 they depend upon the position of the plane (on which the shadow of the 

 earth's axis falls) with respect to 

 the meridian and horizon. Thus 

 if the shadow be receivni upon 

 the Equator E Q, the dial is cal- 

 led an Equatorial Dial ; if upon 

 H R (a great circle of the earth 

 in the plane of the horizon), a __ / 

 Horizontal one ; if upon Z N, J 

 which is in the plane of the 

 prime vertical, a North or South 

 Dial, &c. &c. And in these 

 three last cases, it is obvious 

 that the shadow of the earth's 

 axis, when the sun is on the 

 meridian, or at 12 o'clock, will cut these several circles in Q, R, and N. 

 At 1 o'clock, or when the / Q P 1 is 15, it will cut them at 1, 1', 1"; at 

 2 o'clock, or when the / at P is 30, in 2, 2', 2", &c. ; which are .*, the 

 12 o'clock, 1 o'clock, 2 o'clock, &c, marks. 

 74 



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