( 6140 ) 
Whilfl: the Sea runneth from Weft to Eaft in Flowing, through this 
^^/r^-Jn>/7,therc are no greater Surges, than in any other place of 
the Sea h and in a calm day, it is as fmooth as any Lake, though there is 
conftantly a ^reat current,in the flux and reflux of the Sea. Yet at the 
South-Eaft end of the foreraentioned little Ifland,theSea no fooner be- 
gins to run weft ward in Ebbing,but there beginneth a furge to appear, 
which continually increafech, until the Ebb be half fpent, and after- 
wards it decreafeth, until it be low watery at which time there ap- 
peareth no fuch thing. Eaft and weft from this great Surge, 
there are fome few leffcr furges fcen, which are gradu- 
ally lefs, towards the eaft and weft, after this manner [ 
I having occafion to pafs that way, in a little boat, 
when we had pa{fed over the Eaftmoft furges, and were beginning to af* 
cend the biggeft, upon the tenth ofAprilyn pne of the clock in the after- 
noon,the furge before us was fo high,that it intercepted the fight of the 
Sun, and fome deg. of the firmament above it. This furge is about a 
quarter of a mile in length. When there is any wind, which occafioneth 
the breaking of the tops of the Surges,there is no paffing that way. The 
current of the Tyde is fo ftrong there,that there is no need of Sails or 
of Oaresjfave only to direft the boatjas doth the helm* 
. ContinHatio Excerptornm ex Efiflolu Slufianis & Hugenianis, fnper Alha- 
%ttiiProhlemate OpticoJnAAisPhildfophicisfroxmefragreffis commemorMo. 
]"^N, Hugenim ad noviffimam Dri,SluJii, p. 6123. & feqq. Num. p/, 
^ editam,refcripritEdicori,Xw^/4F^r//7or//««Apr. 9. 1672. in hanc 
fententiara ^ 
Efi qmd Tihi gr atlas agam, quod mnfuifli gravatm Dn. Shifii fuper fro* 
hiemate Alhaziano analyfin mhl tranfmittere. Efi ilia doUilJima & Amhore 
fuodigniffma fuitque in caufay dum earn hi fee diebm examinarem, m novis 
circa frohlema illud medltationihm me tradsrem^eo fpeHambffd , m confirMo- 
nem quam polfem compendioftjjimam maximeque genuinam ohtinerem -^ quam 
tandem me confecmum ejfe reor. Earn hU adfcribamy poftquatn Tibi compen- 
diumjllud tradideroy quod eodem tempore inveni circa primam, ab initio tihi 
communicatam. Id autem tale efi * : Bu^a tinea A T, paral- 
^y.Fj^.h lela C ByCaque bifeEik in F, punEhum hoc efi illudy per quod tran- 
fire debet una hyperbolarnm oppofitarum^ quarum afymptoti in - 
vent^ fuerunt TM, MN. 
Sed en Tihi bonam ill am confiruUionem y qu& in omnibus cafibm obti- 
\ VXig\\. ^^^ f' Sit Circulm datm EByCujm centrum efi; A y vunEla da- 
ta, B & C. 
BhUIs lineis ABy AC y fi ant proportionates BA {radim circuli) & FA : 
Eodem modo C Ay (radim circuli )& GA, T umjmgatur FGy eaqne bifecem 
inHs & per hoc pun^um ducantur tineas. LHKyMHNy fe invicem interfe- 
c antes ad angulos reUos^quarumque L HK fit paralteta eiy qua bifecat angtdum 
MAC, H^funtdH<g. Afymptoti Hyperbolarum defcribendarum per puncia F& 
qum-um una tr anfibit etiam per centrum Ay quarum inter fectiones cm 
circuli- 
