DIALING. 143 



and they will be the true hour-lines, for the like declin- 

 ing, reclining, or inclining dial. And the axis of the cy- 

 linder will always be the gnomon or stile of the dial. 

 For, whichever way the plane of the dial lies,,' its stile 

 (or the edge thereof that casts the shadow on the hours 

 of the day) must be parallel to the earth's axis, and point 

 toward the elevated pole of the heavens. 



To delineate a Sun-dial on Paper; which, when pasted 

 round a Cylinder of Wood, shall shew the Time of the 

 Day, the Sun's Place in the Ecliptic, and his Altitude, 

 at any Time of Observation. See Plate VIII. 



Draw the right line a A B, parallel to the top of the 

 paper; and, with any convenient opening of the com- 

 passes, set one foot in the end of the line at a, as a cen- 

 ter, and with the other foot describe the quadrantal arc 

 A E, and divide it into 90 equal parts or degrees. 

 Draw the right line A C, at right angles to a A B, and 

 touching the quadrant A E at the point A. Then, from 

 the center a, draw right lines through as many degrees 

 of the quadrant, as are equal to the sun's altitude at 

 noon, on the longest day of the year, at the place for 

 which the dial is to serve ; which altitude, at London, is 

 62 degrees : and continue these right lines till they meet 

 the tangent line AC; and, from these points of meet- 

 ing, draw straight lines across the paper, parallel t(. the 

 first right line A B, and they will be the parallels of the 

 sun's altitude, in whole degrees, from sun-rise till sun- 

 set, on all the days of the year. These parallels of al- 

 titude must be drawn out to the right line B D, which 

 must be parallel to A C, and as far as is eq;.al to the 

 intended circumference of the cylinder on which the 

 paper is to be pasted, when the dial is drawn upon it. 



Divide the space between the right lines A C and 

 B D (at top and bottom) into twelve equal parts, for 



