i $6 Mr. Pigott’s Objervaiiom on 
doubtful the observations of 1709 and 1712 are. My two 
make it 487 days ; but as the interval is only a Angle period, 
it may err 10 days ; I therefore (hall take a meail between the 
refults, which is 494, and proceed on to the following compa- 
rifons of Maraldi’s two beft obfervations with mine. 
1708, May 2-, | interval of 56 periods, each of 493 f days, 
1784? Jan. 26, J 
^ 785 * MaJ 2y’J Intervalof 57P erIods * each of 493^ da y s - 
’1 interval of 59 periods, each of 494! days. 
9 J 
interval of 60 periods, each of 494I days. 
A Angle period, on a mean, 494 days. 
1704, Mar. 14, 
1784, Jan. 26 
1704, Mar. 14, 
1785, May 27 
If Maraldi’s obfervations of 1704 and 1708 are exa£t to 
a month, and there is no reafon to believe otherwife, the pe- 
s longer than it 
is at prefent, and therefore the one here deduced may be. 
efteemed as the mean period. 
riod at that time feems to have been a few day 
Particulars of the changes it undergoes. 
1. When at its full brightnefs it is of the 4th magnitude r 
and has no perceptible change for about a fortnight. 
2. It is about Ax months in increafing from the 10th magni- 
tude, and returning to the fame. 
3. Therefore it may be conAdered as inviAble alfo during Ax 
months. 
4. It is conAderably quicker in increaAng than in decreaAng, 
perhaps by half. 
Though 
