OUTLINES OF NATURAL PHILOSOPHY, 



Observe the hour by the clock when the sun's centre 

 is on the meridian ; and observe also the declina- 

 tion of the sun at the same instant. Let the angle 

 at which the sun's path cuts the equator, or what is 

 called the Obliquity of the Ecliptic, = 23.27'.30"; 



find an arch p, such that sin f = ta " Pe ^ . ; 



tan23.27 / .W 



<p has two values, let the least of them, turned into 

 time, =#'. When the sun's declination is north, 

 the hour which the clock should have marked at 

 the time of the observation is $', if it be before, 

 and 12 h <?', if it be after the solstice. When 

 the sun's declination is south, 12-f-p' is the hour 

 if it be before, and 24 q> f if it be after the sol- 

 stice. The error thus found may either be cor- 

 rected or allowed for. The clock is afterwards to 

 be regularly compared with the southing of the 



stars. 

 K> . io a:?'i ink <7K& 'n/la yt. i^ 



'jtrii o . yfinb Ji rfoid*, v.-j . on) 



SO. If a meridian circle pass through any star, 



the arch of the equator intercepted between 

 that circle and the point of the vernal equinox 

 is called the Right Ascension of the star ; and if 

 a clock be regulated as above described, the 

 time of a star's passage over the meridian, when 

 turned into degrees, will be equal to its right 

 ascension, 



_ 

 >>. ij>i . 



a. Suppose 



