APPENDIX. 343 
fix a Pole between the Machine and the Bal- 
lafl:, of fuch a Degree of Strength, that it 
would break before it could give Refinance 
enough to hurt the Machine ; this would 
greatly break its Force againft the Ground. 
Some of the Sand or Earth at the Bottom of 
the Sea (hould be brought up as in common 
Soundings, wdth Tallow at the Bottom of 
the Plummet. 
20. It would be advifeable alfo to keep 
an exaft Account of the time of the Machine’s 
ftay under Water, which may be done by a 
Watch that beats Seconds, or by a Pendulum 
vibrating Seconds, which muft be three Feet 
three Inches and one fifth of an Inch long, 
between the middle of the Bob and the up- 
per end of the Line. 
21. Hook 'm the ThUofoph. Tranfa£i. 
Lowthorp's Abridgment^ Vol. 2. p. 258. found 
upon trial that a leaden Ball which weighed 
two Pounds, being fixed to a wooden Ball 
of the fame Weight, and both let down in 
fourteen fathom Water, they reached the 
Bottom in feventeen Seconds, and the de- 
tached wooden Ball afeended to the Surface 
of the Water in feventeen Seconds more ; fo 
that if the Machine above deferibed defeend- 
2 4 
