Analytical method. Mean, 3. Probable Error, 3. Weights, 4. Probable Error of Two or More Variables, 4. Peirce's Criterion, 6. Diferences, 6. Interpolation, 7. Inverse Interpolation, 8. Numerical Computa tion, 9. Significant Figures, 10. Successive Approximations, 10. Graphical method Interpolation, 12. Residual Curves, 12. Maximo and M inima, 13. Points of In?exion, 13. Asymptotes, 14. Curves of Error, 14. Three Variables, 14. Physical measurements Time, 16. Weight, 19. Length, 19. Areas, 22. Volumes, 22. Angles, 23. Curvature, 25.