EffeB of Electricity in Jhortening Wire. 335 
a fcrew, fo that the wire hung fomewhat loofe between 
them and the lower ones. I then charged a battery, 
containing twenty-fix feet of coated furface, till the index 
of the electrometer was raifed to fifty degrees: it was 
then difcharged through the wire, and, immediately 
after, the wire was feen to fliorten by its drawing nearer 
to a ftraight line between the fixed pinchers. If the wire 
was put fo loofe that the moving of the upper pinchers 
three quarters of a tenth of an inch, or feventy-five 
thoufandths, would draw it juft ftraight, one difcharge of 
the battery through it would then draw it to a ftraight 
line. I difcharged the fame battery nine times through a 
piece of the fame wire, which was alfo of the fame length, 
which was flackened each time before the difcharge 
went through it. There were prefent Sir john pringle, 
the hon. Mr. cavendish, Mr. smeaton, the Rev. Mr. 
michel, Mr. russel, and Mr. whitehurst. After the 
fixth and ninth time Mr. smeaton meafured the wire, 
and found it to have fhortened in the proportion of three 
quarters of a tenth of an inch each time. , 
I afterwards difcharged the battery fix times more 
through the fame piece of wire, which made fifteen 
times in the whole, and found it had continued fhorten- 
ing nearly in the fame proportion, the wire having been 
fhortened by the fifteen ftrokes full one inch and one 
tenth, 
