( |20 )

From these Tables, to any given Tear, Month and Day, to find the next Eclipseof the First Satellite of Jupiter procced thus.

t. In the~Table-©f the Epcchx find the Year öf ourTord, and fet downthe Day, Hours, Mimites and Seconds, vvith Num. I. and Num. II. thcretoannext; and in the Tabie of Revolutions, leek the Month, and Day of theMonth, with die Hours and Minutes, and Num. I. and Mrm. II. affixt, andadd them together ; and the rclpcctive Summs (hall fhew the Mcan Timeof the Middle of the Eciipsc (bught, wich Num. I. and Num II required.

' But it must be ©blerved, that in Jan. and Fcb. in the Leap-Tear, one Day is

to be added to the Day thus found.

2.. If Num. I. be found lefs than 12.2.4, with Num. I. oris the greater than2.448, substracting 2448 therefrom, with the Residue; .enter the Tablc, andyou will Kave the First: T.quation to be Added to the Meari Time beforefound. Butif Num. 1 . be leis than 2448, but greater than 1224, lubstractit from 2448, and entring the fame Tabie with the remainder, you fhall havethe First: ^iquation to be Substracted from the Mean Time. Then dividethe Minutes of the said first jTquation by 11, or rather 'f, and the Quote(hall be the ALquation of Num. 11 . ( answering to the Eccentrick Motion ofJupiter,) to be Added thcreto when the first hEquation Substratis, and c-contra Substracted when that Adds.

3. If Num. II. thus aEquated excced 225,4, Substract 225,4, there-from ; and if the Remainder or Num. II. be leis than 1 13., with the (aid Re-mainder or Number; or if greater than 113, with the Complement thereofto 225, 4, seek in the Tabie the second vEquation, which being Added tothe Time before found, gives the True Time of the Middle of the Eclipse.

4. With Num. I. feek the Half Continuance of the Total Eclipse , whichis to be Added for the Emerson when the /Fquated Num. II. is leis than 11 3,or if more than 225, 4, it belefs than 338: But if it exceed 113, or 338,then is the Semimora tq be Substracted for th e. Immersion.

m. Suf. 5. Lastly, With the Sun s True Place take oyt the T.quation of Natural

Z.XXH Days, which Added or Substracted according to the Title, gives the Timeof the Immersion or Emerson fought.

Now how few Figures ferve for this Computat ion, will best. appear by an

Example.

du. i6jj.