348 FERGUSON'S LECTURES. 



LECT. the north pole, is equal to the elevation of the stile above 

 ^.^^ the plane of the dial. 



If the dial declines westward from the south, count 

 that declination from the east point of the horizon 

 towards the south, and bring the quadrant of altitude to 

 the degree in the horizon at which the reckoning ends ; 

 both for finding the forenoon hours, and the distance of 

 the substile from the meridian : and for the afternoon 

 hours, bring the quadrant to the opposite degree in the 

 horizon, namely, as far from the west towards the north, 

 and then proceed in all respects as above. 



Thus, we have finished our declining dial ; and in so 

 doing, we make four dials, viz. 



1. A north dial, declining eastward by the same number 

 of degrees. 2. A north dial, declining the same num- 

 ber west. 3. A south dial, declining east. And, 4. a 

 south dial declining west. Only, placing the proper 

 number of hours, and the stile or gnomon respectively, 

 upon each plane. For (as above-mentioned) in the 

 south-west plane, the substilar-line falls among the 

 afternoon hours ; and in the south-east, of the same de- 

 clination among the forenoon hours, at equal distances 

 from XII. And so, all the morning hours on the west 

 decliner will be, like the afternoon hours, on the east de- 

 cliner : the south-east decliner will produce the north- 

 west decliner : and the south-west decliner, the north- 

 east decliner, by only extending the hour-lines, stile and 

 substile, quite through the center : the axis of the stile 

 (or edge that casts the shadow on the hour of the day) 

 being in all dials whatever parallel to the axis of the 

 world, and consequently pointing towards the north 

 pole of the heaven in north latitudes, and towards the 

 south pole, in south latitudes. 108 See more of this in the 

 folloicing lecture. 



Note 108. This is evident from the consideration that a plane will 

 be intersected by the meridians of a sphere in the same points, in each 

 cf the four above mentioned positions. 



