E 184 ] 
gin to fhake them both together 
fooner or later, if you continue 
fhaking them for a longer or fhorter 7 
time in one experiment than in 
another, if you cail up the account 
by obferving the degree of the 
meature, or of the brafs fcale, fooner 
or later, &c. you will find in every 
experiment very confiderable yari- 
» ations. | = 
"Sk C- 
