(7*7) 
Tydes there, according to the dire&ions formerly given in "the 
Tr an factions. Ac prefent he a fibre th from many former Obfer- 
' vationss that the biggeft Spring-Tjdes, and Annua! Tydes there, 
are about the ^Equinoxes ? according as the Moon is freer the 
Full; or Change, before or after that time. Of this you may 
expeft a more perfed account hereafter. 
An Extract. 
Of a Letter concerning an optical Experiment, conducive to a de- 
cased Sight, communicated by a Worthy per (on, who found rht 
benefit of it himfelf. 
IAm to acquaint you of an Experiment, if it may deferve that 
name, and nor rather that of a Trifle • the matter of which 
is known to many ? bur un-applied (for ought I know) to fuch 
ufe as it affords. And the ufe is to my fclf of greater value, 
than you'l eafily imagine, and Ithink, it may be equally profita- 
bletomany , Thus it is : you know 5 1 have mourn'd for the lofs 
of my eyes, I confefs my unmanlinefs, that I havefhed many- 
tears in my ftudy for want of them $ but that was quite out of the 
way of recovering them. I know not, whether by (landing 
much before a blazing Fire, or by writing often right before a 
bright Window, or what elfe might be the caufe of this decay 
of my fight, who am not above 60 years of age. But I feem'd 
alwayes to have a kind of thick fmoak or mift about me, and 
fome little black balls to dance in the air about my eyes, and 
to be in the cafe, as If I came into a room fuddenly from a long 
walk in a great Snow, But fo it was, I could not diftinguifh the 
Faces of my acquaintance, nor Men from Women in rooms that 
wanted no light. I could not read the great and black Englifli 
Print in the Church-Bibles, nor keep the plain and trodden paths 
in Fields or Paftures, except I was led or guided. I received 
no benefit by any Glajfes, but was in the cafe of thofe, whofe de- 
cay by Age is greater than can be helped by Spectacles. Thtf ai- 
re fi Prints feemed through Spe&acles like blind Prints, title black 
remaining. 
Being in this fad plight, what trifle can you think hath brought 
me help, which I value more than a great Sum of Gold i Truly, 
L 111 % m 
