OF DIALING. 353 



sines ; and although these are seldom put among the LECT. 

 dialing lines on a scale, yet they assist in drawing the ,X-N 

 line of latitudes. For, if a ruler be laid upon the point 

 .D, and over each division in the line of sines, it will 

 divide the quadrant CB into 90 unequal parts, as Ba, 

 a b, &c. shewn by the right lines 10 a, 20 b, 30 c, ike. 

 drawn along the edge of the ruler. If the right line 

 .B C be drawn, subtending this quadrant, and the near- 

 est distances Ba, Bb, Be, &c. be taken in the com- 

 passes from B, and set upon this line in the same man- 

 ner as directed for the line of chords, it will make a line 

 of latitudes B C, equal in length to the line of chords 

 A B, and of an equal number of divisions, but very un- 

 equal as to their lengths. 



Draw the right line D GA, subtending the quadrant 

 DA; and parallel to it, draw the right line rs, touching 

 the quadrant DA at the numeral figure 3. Divide this 

 quadrant into six equal parts, as 1, 2, 3, &c. and 

 through these points of division draw right lines from 

 the center E to the line r s, which will divide it at the 

 points where the six hours are to be placed, as in the 

 figure. If every sixth part of the quadrant be subdi- 

 vided into four equal parts, right lines drawn from the 

 center through these points of division, and continued to 

 the line r s, will divide each hour upon it into quarters. 



In fig. 2, plate 6, we have the representation of a por- ^ ^ O 

 table dial, w hich may be easily drawn on a card, and * eard - 

 carried in a pocket-book. The lines a d, a b and b c of 

 the gnomon must be cut quite through the card ; and 

 as the end a b of the gnomon is raised occasionally 

 above the plane of the dial, it turns upon the uncut line 

 c d as on a hinge. The line dotted A B must be slit 

 quite through the card, and the thread must be put 

 through the slit, and have a knot tied behind, to keep 

 it from being easily drawn out. On the other end of 

 this thread is a small plummet, and on the middle of it a 

 small bead for shewing the hour of the day. 

 23. ,.\ a 



