London. Bristol. 86 log. 1·93450 70 log. 1·84510 25° tan 9·66867 30° tan 9·76144 ———- ———- 1·60317 = 40·1 1·60654 = 40·4 so that the observations accord very closely in fixing the height at a little exceeding 40 miles at disappearance, but a slight correction is necessary to allow for the Earth’s curvature. There are other methods of computing the heights, one of which is explained by Prof. A. S. Herschel in a paper entitled “Height of a Meteor” (‘Monthly Notices,’ vol. xxv. p. 251). _Meteoric Observations._—A large number of meteor-showers still await discovery, and there are features even in connection with the best known streams which remain to be elucidated. Such doubts as now exist are only to be cleared away by assiduous observation made with the utmost accuracy possible both of the _directions_ and _durations_ of meteors. This attractive field of investigation has certainly been neglected in recent years, and the reason of this may perhaps be found in the complications inseparable from it, in the need of great patience and scrupulous care in observation, and the necessity of gaining experience before the observer can feel a reliance on his work, and draw safe conclusions. Meteors are so fugitive, so diverse and erratic in their apparitions, as to be quite beyond the scope of instrumental refinements. They must necessarily be observed under many disadvantages. Positions have to be fixed from very hurried and often imperfect impressions. But these drawbacks, formidable as they at first appear, may be severally overcome by practice, by careful regard for the conditions under which meteors are displayed, and the marked differences of aspect induced by these conditions. When the observer has acquired a practical knowledge he will proceed with confidence in his work, and avoid many of the difficulties surrounding it.