[ 3 
nute^ moft exaftly in the Dial. By the fame Telefcoplcal 
Sight, the motion of the Sun will be perceived fo quick and 
nice, that two beats oi^i Seccrd-ierdulum Oiay be determined, 
and the time of the day orniglit to 5, or ; Seconds diicer- 
ned. The way of ufiog this Dial on the Stars by Night is 
much the fame, only that for theie are requifite certain 
Tables (^put at the end of the Bools^ of the Sun and Stars tem- 
porary Right-Afcenfions : For in looking at the Star through 
the Telefcopick-Ruler, the Horizontal-Ruler cuts the Stars 
horary diflance from the Meridian, to which adding the 
Stars Right Aicenfion,and from the fum fubftrafting the Suns 
Right Aicenfion, the remainder gives the Hour, Minute, 
and Second of the Night ; and by this Method inverted, the 
Author thinketh the Right Afcenfion of any Star may be 
cafily had. The way to calculate the Suns and Stars Alcen- 
iions, he declareth in the ^th. Chap, and alio Chap i o, tlie 
Equation of Time, upon fuppofition of the equabiUty of the 
Earths Revolutions ; he fhows alio by a Calculus how to 
corrcflt the length of the VenMum of a Clock, and giveth 
Samuel Smithy at the Frinces Arms in St. Faul 
Church Yard. 
