Si III electron temperature diagnostics for the solar transition region

R-matrix calculations of electron impact excitation rates for transitions in Si iii are used to derive the electron-density-sensitive emission line ratios R₁ = I(1113.2 Å)/I(1206.3 Å), R₂ = I(1298.9 Å)/I(1206.3 Å), and R₃ = I(1296.7 Å)/I(1206.3 Å). A comparison of these with observational data for several solar features obtained with the Harvard S-055 spectrometer on board Skylab reveals that theory and experiment are compatible if the electron temperature of the Si iii emitting region of the solar atmosphere is log T_e= 4.5, but not if log T_e= 4.7. The implication of the choice of a lower temperature on the electron energy distribution function is also briefly discussed.