444 SUPPLEMENT. 



the twelve signs of the ecliptic ; and, from mark to 

 mark, of these divisions at top and bottom, draw right 

 lines parallel to A C and B D; and place the charac- 

 ters of the 12 signs in these twelve spaces, at the bot- 

 tom, as in the figure : beginning with yf or Capricorn, 

 and ending with x or Pisces. The spaces including 

 the signs should be divided by parallel lines into halves ; 

 and, if the breadth will admit of it without confusion, 

 into quarters also. 



At the top of the dial, make a scale of the months 

 and days of the year, so that the days may stand over 

 the sun's place for each of them in the signs of the 

 ecliptic. The sun's place, for every day of the year, 

 may be found by any common ephemeris : and here it 

 will be best to make use of an ephemeris for the second 

 year after leap-year ; as the nearest mean for the sun's 

 place on the days of the leap-year, and on those of the 

 first, second, and third years after. 



Compute the sun's altitude for every hour (in the la- 

 titude of your place) when he is in the beginning, mid- 

 dle, and end of each sign of the ecliptic ; his altitnde 

 at the end of each sign being the same as at the begin- 

 ning of the next. And, in the upright parallel lines, at 

 the beginning and middle of each sign, make marks 

 for these computed altitudes among the horizontal pa- 

 rallels of altitude, reckoning them downward, accord- 

 ing to the order of the numeral figures set to them at 

 the right hand, answering to the like divisions of the 

 quadrant at the left. And, through these marks, draw 

 the curve hour-lines, and set the hours to them, as in 

 the figure, reckoning the forenoon hours downward, and 



the afternoon hours upward. The sun's altitude 



should also be computed for the half hours ; and the 

 quarter lines may be drawn, very nearly in their proper 

 places, by estimation and accuracy of the eye. Then, 

 cut off' the paper at the left hand, on which the quadrant 



