254 



If a mass of water is thrown into the air, and allowed to fall 

 on soft clay, the form of the impression will depend upon the 

 condition of the drops at the time of contact. In descending, 

 the drops assume the following forms, viz : first, that of a flat- 

 tened sphere ; second, that of a cup with the concavity down- 

 wards ; third, that of a ring ; and fourth, those of two or more 

 spheres formed by the rupture of the ring. 



If the sphere be above a certain size, the impression presents 

 a reticulated appearance in the centre, with radiating lines around 

 the circumference. The impression formed by the cup is retic- 

 ulated in the centre without radiating lines. The ring forms an 

 impression corresponding with its shape, with radiating lines on 

 its inner border, and sometimes on its outer border. 



Prof. Wyman thought that rain marks could be distinguished 

 from those of spray. 



The rain mark is modified by the condition of the surface on 

 which it strikes ; if the latter is hard, or of a coarse material, 

 the minuter details are not shown. On examining the fossil 

 rain marks, he had not found that the radiating lines were pre- 

 served. They were doubtless destroyed by the drifting in of the 

 new material by which they were covered up. In other respects, 

 they resembled recent rain marks, and could be accounted for in 

 no other way, than by the contact of drops of falling water. 



Sonne discussion ensued upon the rain and spray im- 

 pressions, in which the President, Dr. Jackson, Dr. Hayes, 

 Dr. Abbot, and Mr. Bouvc took part. They all recognized 

 the great value of Prof. Wyman's investigations, as valua- 

 ble contributions to science, and hoped that he would con- 

 tinue these practical demonstrations in other and different 

 materials. 



The Librarian announced the following bequest to the 

 Society, by the late James Brown, one of the Patrons of 

 the Society : — 



" I give and bequeath to the Boston Society of Natural His- 

 tory, Gould's Ornithology, in sixteen volumes, folio ; Cuvier's 



