[ 10 J

had attributed in his former table to the Cuinei u1682, he substituted new Tables of an Elliptic one,and then try’d if Mr. Flamftead 's Observationson this very Comet, and which were taken witha very large and accurate sextant, and duly clearedfrom refractions, would correspond with hisTheory.

Now it is manifest by the Catalogue, that twoperiods of this Comet amount to 151 years nearly,and that they are alternately greater and less, theone of 56, and the other of 55 years ; afterwardsapplying this and other data, as directed by 15Prop. x st book of Newton's. Principia , by the helpof his new Tables, he finds, that on the 30th ofAugust, 1682,

The place of this Comet according to his Theory

was,

deg.

min.

fee.

and according to a real'

Libra

*5

35

58

observation made byFlamsead it was,

. Libra

15

34

42

And its North Latitude according to his Theory

was,

deg. min. fee.17 24 42

and by a real observationmade by Pi anise ad

Now the Difference between the computed andobserved places, is but 1' 16', and that of theirLatitudes only 45", which difference he thinks

deserves

17 24 46