2. _The Number of Aerolites._--The average number of aerolitic falls in a year was estimated by Schreibers, as previously stated, at 700. Reichenbach, however, after a thorough discussion of the data at hand, makes the number much larger. He regards the probable annual average, for the entire surface of the earth, as not less than 4500. This would give about twelve daily falls. They are of every variety as to magnitude, from a weight of less than a single ounce to over 30,000 pounds. The Baron even suspects the meteoric origin of large masses of dolerite which all former geologists had considered native to our planet. In view of the fact that from the largest members of our planetary system down to the particles of meteoric dust there is an approximately regular gradation, and that the larger, at least in some instances, appear to have been formed by the aggregation of the smaller, he asks may not the earth itself have been formed by an agglomeration of meteorites? The learned author, from the general scope of his speculations, would thus seem to have adopted a form of the nebular hypothesis somewhat different from that proposed by Laplace. 3. _Composition and mean Density of Aerolites._--A large proportion of meteoric stones are similar in structure to the volcanic or plutonic rocks of the earth; and _all_ consist of elements identical with those in our planet's crust. Their mean density, moreover, is very nearly the same with that of the earth. These facts are regarded by Reichenbach as indicating that those meteoric masses which are daily becoming incorporated with our planet, have had a common origin with the earth itself. Baron Reichenbach's views, as presented by himself, will be found at length in _Poggendorf's Annalen_ for December, 1858.