In order to ascertain the relative accuracy of various methods of measuring areas, Prof. Goodman has had a large number of irregular areas measured by his first year students within a week or so of their entering the department, before they have attained to any degree of skill in using instruments. The results were as follows. Amsler's planimeter was taken as the standard, the area measured by it being independently checked by an assistant. Measurement of Areas Method. Reduced to 100. Amsler planimeter 100 Goodman " 100 + or - 0.6 Simpson's rule 100 + or - 1.0 Mean ordinates 100 + or - 2.4 Cutting out in cardboard and weighing against piece of known area 100 + or - 4.4 Equalizing curved edges by drawing straight lines along boundary and calculating by triangles 100 + or - 7.0 In the averaging instrument for getting mean heights of figures, the length of the instrument between the hatchet and the pointer is variable. The length is set to the length of the diagram (see Fig. 2); it is then used in precisely the same manner as the planimeter described above. From what we have already said, our diagram in Fig. 5 will be perfectly clear. The mean distance between the dents is in this case the mean height of the diagram, measured on an ordinary scale, or the mean pressure in the case of an indicator diagram measured on a scale to suit the indicator spring.