q6 Dr. Herschel’s Miscellaneous Observations. 
in order to reconcile all observations, to admit of some occa- 
sional deviations in the appearance of the star, amounting 
almost to a month ; but that this is no more than we may allow, 
is pretty evident from the variations I have taken notice of 
within the last 14 years ; besides, a period of 334 days could 
not be admitted without totally giving up ail regularity in the 
returning appearance of the star. 
I have taken the epoch of the 21st of October, 1790, as one 
of the best ascertained, moderate appearances I have been able 
to obtain ; and believe it to be more proper for settling the 
period, than that which might be deduced from a brilliant blaze 
of the star, such as took place in 1779, owing to causes that 
are not regular, and therefore may be apprehended to disturb 
the general order of the change. 
On the Disappearance of the 55th Herculis. 
Among the changes that happen in the sidereal heavens we 
enumerate the loss of stars ; but, notwithstanding the real de- 
struction of an heavenly body may not be impossible, we have 
some reasons to think that the disappearance of a star is proba- 
bly owing to causes which are of the same nature with those 
that act upon periodical stars, when they occasion their tem- 
porary occultations. This subject, however, being of great 
extent and consequence, we shall not enter into it at present, 
but only relate a recent instance of the kind. 
Two stars of the 3th magnitude, whose places we find in- 
serted in all our best catalogues, were to be seen in the neck 
of Hercules. They are the 54th and 55th of Flamsteed's, in 
that constellation. In the year 1781, the 10th of October, I 
