350 FERGUSON'S LECTURES. 



V through the center c to the other side of the dial, for 

 the like hours of the morning ; which done, lay the ruler 

 on the point a, and draw the last five hours in the fore- 

 noon through the dots 5,4,3,2,1, on the Ymefb; 

 continuing the hour-lines of VII and VIII through the 

 center a to the other side of the dial, for the like hours 

 of the evening ; and set the hours to their respective 

 lines as in the figure. Lastly, make the gnomon the 

 same way as taught above for the horizontal dial, and 

 the whole will be finished. 



To make an erect south dial, take the co-latitude of 

 your place from the scale of latitudes, and then proceed 

 in all respects for the hour-lines, as in the horizontal 

 dial ; only reversing the hours, as in Fig. 2 : and making 

 the angle of the stile's height equal to the co-latitude. 



I have drawn out a set of dialing lines upon the top 

 of the sixth plate, large enough for making a dial of nine 

 inches diameter, or more inches if required ; and have 

 drawn them tolerably exact for common practice, to 

 every quarter of an hour. This scale may be cut oft* 

 from the plate, and pasted on wood, or upon the inside 

 of one of the boards of this book ; and then it will be 

 somewhat more exact than it is on the plate ; for being 

 rightly divided upon the copper plate, and printed off 

 on wet paper ; it shrinks as the paper dries : but when 

 it is wetted again, it stretches to the same size as when 

 newly printed ; and if pasted on while wet, it will re- 

 main of that size afterward. 



But lest the young dialist should have neither globe 

 nor wooden scale and should tear or otherwise spoil the 

 paper one in pasting, we shall now shew how him he 

 may make a dial without any of these helps. Only, if he 

 has not a line of chords, he must divide a quadrant into 

 90 equal parts or degrees for taking the proper angle of 



the stile's elevation, which is easily done. 18 * 



^ 



Note 109. The instsament called the protractor will be found 



qually convenient. 



