long Wire-ftapie B,in the Ball A, and a fpringing wire C, with a 
bended end F, and into the faid Staple, prefs in with your fingers 
the fpringing Wire on the bended end : and on it hang the weight 
D, by its hook E, and fo let Globe and all fink gently into the 
Water, in the pofture reprefented in thefai dFigure, to the bot- 
tom , where the weight X> touching firft , is thereby fiopt > but 
the Ball, being by the Impetus it acquired in defcending , carried 
.downwards a little after the weight is ftopc , fuffers the fpringing 
Wire tolly back , and thereby fets itfelf at liberty to re-afcend. 
And by obferving rhe timeof the Ball’s ftay under Water (which 
maybe done by a Watch, having Minutes and Seconds; or by a 
good Minute-Glafs ; or beftof all, by a Pendulum^ vibrating Se- 
conds - 7 the which muft be three foot, three inches, and one fifth of 
an inch long, viz. between the middle of the Bullet and the up- 
per end of the Thred , where it is faftned,or held when it vibrates.) 
You may by this way , with the help of fome Tables , come to 
know any depth of the Sea. 
Note y That caremuftbe had of proportioning the weight and 
ihapeof th zLead^ to the bulk, weight, andfigure of the Globe y 
after fuch a manner , as upon experience (hall be found moft con- 
venient. 
In fome of the Trials already made with this Inftrument, the 
Globe being of Maple-mod , well covered with Pitch , to hinder 
foaking in , was 5 11 inches, in Diameter , and weighed 2 ] pounds 5 
the Lead, of 4* pounds weight , was of a Conical ( but^now u- 
fedof a Globous ) Figure 1 1 inches long, with the (harper end down- 
wards , i,,! at the bottom in Diameter. And in thofe Experiments 
iinade in the Thames , in the depth of 19 foot water , there paf- 
fed between the Immerfion and Emerfion of the Globe , 6 Se- 
conds of im hour-; and in the depth of 10 foot water , there paf- 
fed Seconds,or thereabouts: From many of which kind of Ex- 
periments, it will likely not be hardto find outa method to calcu- 
late , what depth is to be, concluded from any time of the like 
Globes flay under water : As for in fiance , if in the depth of 20 fa- 
rthom , meafured by the Line , the Globe ftay under water 1 5 Se- 
conds ; then if the Ball ftay 700 Seconds , the depth of the Sea is 
9$$ fathom and 2 foot , if the Bali be found to move equal fpaces 
tin equal time. 
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