■ JSiifceUanea Curio fa. 209 



bh which you take the made, or that of the 

 Line therein, on which you meafure the Re- 

 cefs of the Sun from the Tropick, very ma- 

 terial ; but in what way foever you difcover 

 - it, the faid" Recefs will be always in the fame 

 Proportion, by reafon of the fmalnefs of the 

 .Angle, which is not fix Minutes in the firfh 

 I five days : Nor need you enquire the height 

 or diftance of your Building, provided it be 

 very great, fo as to make the Spaces you 

 meafure large and fair. But it is convenient 

 that the Plane on which you take the made 

 be not far from Perpendicular to the Sun, at 

 lea ft not very Oblique, and that the Wall 

 which cafts the made, be ftraight and fmooth 

 at Top, and its Direction nearly Eaft and 

 Weft, for Reafons that will be well under- 

 flood by a Reader skilful in the Doctrine of 

 the Sphere. And it will be requifite to' take 

 the Extream greater! or leaft Deviation of 

 the fnadow of the Wall, becaule the- fliade 

 continues for a good Time at a Hand, with- 

 out alteration, which will give the Qbferver 

 lei fare to be aHur'd of what he does, and not 

 be furpriz'd by the quick tranflent Motion 

 of the made of a fmgle Point at fuch a dl- 

 jftance. The principal Objection is, that the 

 Penumbra or Partile made of the Sun, is iii 

 ks Extreams very difficult to diftinguiih from 

 the true made, which will render this Obfer- 

 vation hard to determine nicely. But if the 

 Sun be tranfmitted through a Ttlefiope, after 

 the manner us'd to take his Species in a Solar 

 Eclipfe, and the upper half of the Object- 

 glafs be cut off by a Paper palled thereon* 

 and the exact upper Limb of the Sun be feeii 

 g - pit 



