( SO I I ) 
17. Demonftrates, how much weight of water there Iietfi 
againft a Ship moving at Sea j having firft laid down certain 
propofitions made ouc by Stevinus in his Hydrojlattcks 5 which 
Writers foot-fteps our Author acknowledgeth to have fol- 
lowed herein. Befides he exaijiiLis alfo the Center of Gravity of 
a Ship j which being knowo^ it may be certainly concluded^ 
Ho w a Ship is to lye upon the water, and how heavy it is when 
'cis floatingjwhether loadeo or uaioaden^Laftly he imparts the 
way of the Excellent Hudde^ of calculating exad:ly, what bur^ 
then a fliip can carry either in Salt or Sweet water > Where he 
alio examins the weight of the waterj in which a Ship is float- 
ing i for which purpofe he caufed to be made a Cube of Cop- 
per-plates, of half an Amiterdam-foot a fide, fitted after a 
certain manner^too particular to be here relatedjwhereby he 
found, that upon the 15^/; of March ^ a foot of 'R^ain ivater 
weighed_49/^. J4^ounces5 and T^^i^^^^r, 46 2|ounccs 5 and 
lexel-rvMer^^^S ib, 9 ounces* To all which he adds the way of 
meafuringthcQiiantity of a Ship's burthen, that hath been a- 
greed upon between the King of Denmark and the States of 
the United Provinces j as alio feveral ways of doing the fame, 
ufed by.other Nations^and particularly that of the Englifb and 
French, 
iBt Explains and gives rcafons for the fcvera! fizes and 
fliapes of the parts of a fhipj as why the Mafts ought juft to be 
of fuch a hulk and height/ Why fome of them muft incline 
backwardjfome ftand upright > Why a fraall Rudder can turn 
agreatShip- and a little Anker ftay itf What makeih Ships 
not fee-1 the Rudder f* Why Veflels too broad are weak and 
prove inconvenient in high Winds ? Why long and moderate^ 
ly narrow Ships endure the Sea better, than Oiort and broad 
ones? How the Keel ought to be placed f ^[ly Gallions ^ud 
the parts of them are fram'd as they are ? Why a Ship is to be 
broader before,then a ban f That Fregars, built long, narrow 
and loWjfai! beft. What hinders welLl'aiiing / Why Turk ill 
VeflTels are excellent Sailers ? And many qneltions more^con- 
lidered by this Author. 
i9,Reckons up the particulars of theloofe apparatus necef- 
fary in a moderately far Voyage for an hundred men, in a (hip 
154 toot long.both for her condud and defence^and theFocd 
of the Marrincrs> And 
