JVIifcellanea Curiofa. 203 



mide near the Tropick, at proper Intervals 

 of Time, I hereby delign to lhew a Method 

 to find the Moment of the Tropicks capable 

 of all the Exa&nefs the moft Accurate can 

 defire ; and that without any confideration 

 of the Parallax of the Sun, of the Refracti- 

 ons of the Air, of the greateft Obliquity of 

 the Ecliptick, or Latitude of the Place : All 

 which are requir'd to afcertain the Times of 

 the Equinoctials from Obfervation , and 

 which being faultily alTum'd, have occafion'd 

 an Error of near three Hours in the Times 

 of the Elquino&ials deduced from the Tables 

 of the Noble Tycho Brake and Kepler, the 

 Vernal being fo much later, and the Au- 

 tumnial fo much earlier than by the Calcuim 

 of thofe Famous Authors. 



Now before we proceed, it will be necef- 

 fary to premife the following Lemmata, fer- 

 ving to demonftrate this Method, viz.. 



1. That the Motion of the Sun in the 

 Ecliptick, about the Time of the Tropicks, 

 is fo nearly equable, that the difference 

 from Equality is not fenfible, from five days 

 before the Tropick, to five days after : And 

 the difference ariling from the little Inequa- 

 lity that there is, never amounts to above 

 ■4 of a fingle Second in the Declination, and 

 this by reafon of the nearnefs of the jijo- 

 g&on of the Sun to the Tropick of Cancer. 



2. That for five Degrees before and after 

 the Tropicks, the differences whereby the Sun 

 falls fhort of the Tropicks, are as the verfed 

 Sines of the Sun's diftance in Longitude from 

 the Tropicks, which verfed Sines in Arches 

 under five Degrees^ are beyond the utmoft 



nicety 



