On January 29, 1977, an auroral arc remained in the field of view of the Chatanika incoherent scatter radar for about 1 hour. Prolonged measurements were made of the line-of-sight velocities and densities from roughly 80- to 250-km altitude within and on both sides of the arc. From these basic measurements electric fields, conductivities, currents, and heating rates were calculated. In spite of the fact that the arc changed its appearance considerably over the hour, the measured and calculated parameters remained qualitatively very much the same. The northward electric field was very strong and showed a latitudinal profile similar to that frequently observed on satellites. One hundred (100) km equatorward of the arc the field was ~30 mV/m; from that point it increased to over 100 mV/m at the equatorward edge of the arc. The field then dropped sharply to ~30 mV/m within the arc. The northward field did not change across the poleward edge of the arc, indicating that there was no polarization effect. The latitudinal profile of the calculated horizontal currents suggests that the major downward field aligned currents are located in the region equatorward of the arc and the upward currents at the equatorward edge of the arc. The integrated joule heating rate peaked just equatorward of the arc, reaching a value of over 150 ergs cm-2 s-1; inside the arc it dropped to 20--40 ergs cm-2 s-1. The particle heating rate was negligible outside and was 10--30 ergs cm-2 s-1 inside the arc. The joule heating always exceeded the particle heating.