A high-resolution, flat-field, plane-grating, f/10 spectrometer based on the novel design proposed by Gil and Simon [Appl. Opt. 22, 152 (1983)] is demonstrated. The spectrometer design employs off-axis parabolic collimation and camera mirrors in a configuration that eliminates spherical aberrations and minimizes astigmatism, coma, and field curvature in the image plane. In accordance with theoretical analysis, the performance of this spectrometer achieves a high spatial resolution over the large detection area, which is shown to be limited only by the quality of its optics and their proper alignment within the spatial resolution of a 13\mu \text{m}\times 13\mu \text{m} pixelated CCD detector. With a 1500\text{lines}/\text{mm} grating in first order, the measured spectral resolving power of \lambda /\Delta \lambda =2.5\left(\pm 0.5\right)\times {10}^4 allows the clear resolution of the violet \text{Ar}\left(\text{I}\right) doublet at 419.07 and 419.10\text{\hspace{0.17em} nm} .