B. I). Josephs Current Fig. 2. Predicted two-part current-voltage characteristic of a superconducting tunnel missing supercurrents, which was sufficiently convincing for me to decide to alculation, (14)although it turned out lat the critical supercurrent and the normal state resistivity depended on the assumption of time-reversal symmetry, which would be violated if a magnetic field were present. I was able to calculate the magnitude of the effect by using the Ginzburg- Landau theory to find the effect of the field on the phase of the f functions, and concluded that the earth's field could have a drastic effect on the supercurrents Brian Pippard then suggested that I should try to observe tunneling super currents myself, by measuring the characteristics of a junction in a compe sated field. The result was negative-a current less than a thousandth of the predicted critical current was sufficient to produce a detectable voltage across the junction. This experiment was at one time to be written up in a chapter of my thesis entitled'Two Unsuccessful Experiments in Electron Tunnelling between Superconduct Eventually Anderson realized that the reason for the non-observation of dc supercurrents in some specimens was that electrical noise transmitted down the measuring leads to the specimen could be sufficient in high-resistance161 : Current Fig. 2. Predicted two-part current-voltage characteristic of a superconducting tunnel junction. Then a few days later Phil Anderson walked in with an explanation for the missing supercurrents, which was sufficiently convincing for me to decide to go ahead and publish my calculation, (14) although it turned out later not to have been the correct explanation. He pointed out that my relation between the critical supercurrent and the normal state resistivity depended on the assumption of time-reversal symmetry, which would be violated if a magnetic field were present. I was able to calculate the magnitude of the effect by using the Ginzburg-Landau theory to find the effect of the field on the phase of the F functions, and concluded that the Earth’s field could have a drastic effect on the supercurrents. Brian Pippard then suggested that I should try to observe tunneling super￾currents myself, by measuring the characteristics of a junction in a compen￾sated field. The result was negative-a current less than a thousandth of the predicted critical current was sufficient to produce a detectable voltage across the junction. This experiment was at one time to be written up in a chapter of my thesis entitled ‘Two Unsuccessful Experiments in Electron Tunnelling between Superconductors’. Eventually Anderson realized that the reason for the non-observation of dc supercurrents in some specimens was that electrical noise transmitted down the measuring leads to the specimen could be sufficient in high-resistance