736 



PHILOSOPHICAL TRANSACTIONS. 



[anno 1790. 



another season to come to some degree of accuracy ; till when he states it at 



The distance of these satellites, deduced from calculation, depends entirely on 

 the time and distance of the 4th, which is the satellite that has been used. In 

 order to obtain more accuracy in these elements, he applied himself to mea- 

 suring the distance of the 4th satellite in those moments which were most 

 favourable for the purpose. It is well known that this subject, on account of 

 the quantity of matter in Saturn, to be deduced from the periodical times and 

 distances of the satellites, is of considerable importance to astronomers; he there- 

 fore defers a full investigation of it till he can have an opportunity of calculating 

 a great number of measures, not only of the 4th and 6th, but also of the other 

 satellites which he had already by him, and still intends next season to take. 

 Mean while, having brought the measures of the 30th of November, which 

 seem to be very good ones, to the mean distance of Saturn from the sun, he 

 finds they give the distance of the 4th satellite from Saturn 3' 8".918. In redu- 

 cing these measures to the mean distance, he used the new tables of De Lambre 

 for Saturn, and Mayer's for the sun. Admitting therefore the above quantity 

 as the distance, and 15^^ 22^ 41"^ l3^4 as the period of the 4th satellite, we 

 compute that the distance of the 6th from the centre of Saturn is 36^7889; 

 and that of the 7 th, 28'^6689. 



Tables for the seven satellites of Saturn. 



Epochs of the mean longitude of the satellites. 



In tlie months January and February of a bissextile year substract 1 from the num- 

 ber of days given. 



