204. MifceUanea Curio fa. 



nicety of Senfe, as the Squares of thofe Arches. 

 From thefe two follow a third : 



3. That for five days before and after the 

 Tropicks, the Declination of the Sun falls 

 fhort of the utmoft Tropical Declination, by 

 Spaces which are in duplicate Proportion, 

 or as the Squares of the Times by which 

 the Sun is wanting of or pail the Moment 

 of the Tropick. 



Hence it is evident that if the Shadows 

 of the Sun, either ' in the Meridian or any 

 o*ther Azimuth, be carefully obferv'd about 

 the Time of the Tropicks, the Spaces where- 

 by the Tropical made falls fhort of, or ex- 

 ceeds thofe at other Times, are always pro- 

 portionable to the Squares of the Intervals 

 of Time between thofe Obfervations and the 

 true Time of the Tropick, and confequently 

 if the Line, on which the Limits of the made 

 is taken, be made the Axis, and the corre- 

 ■fpondent Times from the Tropick expound- 

 ed by Lines, be ere&ed on their refpe&ive 

 Points in the Axis as Ordinates, the Extre- 

 mities of thofe Lines mail touch the Curve 

 of a Parabola-} as may be feen in the Fi- 

 gure : Where a, b, c, e, being fuppofed 

 Points obferved, the Lines a B, b C, c A, 

 eF, are refpedively proportional to the 

 Times of each Obfervation before or after 

 the Tropical Moment' in Cancer. 



This premifed, w T e mall be able to bring 

 the Problem of rinding the true Time of the 

 Tropick by three Obfervations, to this Geo- 

 metrical one ; having three Points in a Pa-r 

 rabola A, B, C, or A, F, C given, together 

 with the direction of the Axis, to find the 



