Generally the violin players use the E string.
Sometimes he used a slightly lighter high E string (.012 or .011).
Most E strings are unwound, either plain or gold-plated steel.
Since modern E strings are steel, a fine tuner is typically fitted for that string.
However the A and lower E strings were single.
The low E string was added during the 18th century.
This was accomplished by using his right hand to pick a single-note trill on the high E string.
"Now I'll have to go get a new E string," he complained.
I did encounter a problem with the low E string, but I'll come to that in a while.
Now repeat the procedure for the bottom E string.