At both junctions, use pliers to twist the copper and constantan wires together
tightly as shown below. Use enough constantan so one junction can be in
an ice bath while you probe with the other. You cannot measure the junction
voltage directly, but you can measure the difference between two junctions
at different temperatures. Always leave one junction in ice waterp;the
"reference junction." Measure the voltage between the two copper
wires as you change the temperature of the other junction.
