THE formulæ which Mr. Percival gives in NATURE for March 18 for approximate integration are well known, but there are one or two points in connection with them which are frequently overlooked, ...

To approximate the definite integral we split the region up into many thin slices. For each slice we may approximate its area using rectangles, in which case we could either use right-endpoints, ...

To approximate the definite integral we split the region up into many thin slices. For each slice we may approximate its area using rectandles, in which case we could either use right-endpoints, ...