observations entering into each average. The small circles are connected by straight lines. The smooth curves in each case are obtained by combining, by means of a mathematical analysis, the results at all

Fig. 5. Observations taken at Mizusawa, Tschardjul, Carloforte, Gaithersburg, Cincinnati, Ukiah. (Reading from the top, down.)

of the stations into a general result, and then from this general result computing the variation of the latitude for each individual station. The vertical distance between any small circle and the smooth curve will be, very nearly, the actual error of the average result represented