the changeable Stars . 
1 95 
Variable in Hydra,, 
Maraldi, in 1704, having found that this ftar had a pe- 
riodical variation, continued to examine it for feveral years, 
and concluded its period to be about two years, though with 
confiderable variations ; in which he was much miftaken, as 
will appear from the following refults, which fhew that its 
period in all probability is tolerably regular, and only of 494 
days. 
Dates when it was at the middle of its greateft brightnefs, 
eftimated from Maraldi*s obfervations. 
1704, March 14, he favv it nearly of the fame magnitude 
from the beginning of March until the 
beginning of April; it then decreafedo 
^705, . . he faw it very faint in November, 1705, 
and found it decreafing : this obfervation 
is too im perfect. 
51708, May 22, accurately determined ; its increafe and de« 
creafe being well obferved. 
3709, Nov. 10, :: doubtful, its decreafe only being obferved. 
1712, May 1, :: ditto, ditto, ditto. 
1784, Jan. 26, by me, very accurately, its increafe and 
decreafe being obferved. See the Obfer- 
vations that conclude this paper. 
1785, May 27, ditto, ditto, ditto. 
The four greateft intervals of Maraldi’s Obfervations give 
for fingle periods in days thus 495 — 517—480 and 510, the 
mean being 500 1, which is tolerably exa<St confidering how 
C e 2 doubtful 
