o F T n E P L iV N E T S. 6g 



Then to U* =: ss'^' 26' 57* Log ung^ lo.i '2^ (.o^ 



Add half the fum of the log', of the aphelion and perihelion dill. 6.2&00876 



16.4421281 

 Deduft the log. of the mean dift. 6.2 80 5800 



I'he remainder is the log. tang', of 55° 25' 7* 10.1615481 



The co-equ;ite or true anomaly ^^^ 15 7' is the meafiire of. 

 the angle AC r, and when dedufted from the mean anomaly 

 will leave the equation of the centre : as for example, ^^° 25' 7" 

 tak*;n from 60-'' the mean anomaly ufed in the foregoing expla- 

 nation the remainder 4" 34' ^t," will be the equation of the 

 centre anfwering to it. — The equation of the centre muft be 

 negatively applied while the planet is moving from the aphelion, 

 to the perihelion, and vice •vcrfa. 



I am, Sir, with much efteem, 



Your real Friend, 



ANDREW ELLICOTT. 



Te Mr. Robert Patter/on. 



K\ IX. 



Method of raifing the common Logarithm of any Number im^ 

 tnediatelyy by David Rittenhouse, Prejident of the St- 

 ciety. 



Read Aug. T^HE logarithm of any number is the index of that 

 I*. J 795- X power of 10 which is equal to the given num- 

 ber. This index will always be fraftional, unlefs the number 

 be divifible by 10 without any remainder. 



If the number be greater than 10, divide it by the higheft 

 power of ID that will leave the quotient not lefs than i. The 

 index of that power is the firft figure, or index of the logarithm. 

 Divide i o by the quotient fo found raifed to the higheft power 

 that will leave the new quotient not lefs than unity. Divide 



* Nnte. When U exceeds 90° take its fupplement and in that cafe dedud 

 the refuli of the calculation from two right anghs, and the remainder will 

 be the true anomaly. 



K the 



