extreme limit of diminution to which repeating circles, designed for astronomical purposes, ought to be carried.
"The practical value of the six-inch repeating circle may be estimated, by comparing the differences of the partial results from the mean at each station, with the correspondence of any similar collection of observations made with a circle, on the original construction, and of large dimensions; such, for instance, as the latitudes of the stations of the French arc, recorded in the Base du Système Metrique: when, if due allowance be made for the extensive experience and great skill of the distinguished persons who conducted the French observations, the comparison will scarcely appear to the disadvantage of the smaller circle, even if extended generally through all the stations of the present volume; but if it be particularly directed to Maranham and Spitzbergen,—at which stations the partial results were more numerous than elsewhere, and obtained with especial regard to every circumstance by which their accuracy might be affected, the performance of the six-inch circle will appear fully equal to that of circles of the larger dimension. The comparison with the two stations, at which a more
