Some of these, which may be called " earth-tremors," resemble earthquakes in the rapidity with which they occur, but differ from earthquakes in being imperceptible (owing to the smallness of the motion) until instrumental means are used to detect them.
This difference is very large compared with the smallness of the unit.
Yet his observations are of the first importance as showing the smallness of the deviation of the central line from the ecliptic. When smoothed out, the maximum latitude is less than 3°, which seems to preclude the coincidence of the central plane of the light with that of the sun's equator.
The smallness of the trade with Portugal is partly due to the similarity of the chief products of the two countries.
Fleming select lead on account of the smallness of the Thomson effect in it, as observed by Le Roux.