794 



SCIENCE. 



[N. S. Vol. XXII. No. 572. 



fore, to bring out the phenomenon in such a 

 way as to divest it of its paradoxical features. 

 Perhaps the most insinuatingly paradoxical 

 aspect of the phenomenon is that which is 



^ 



rJe 



2D 



d r d 



Fig. 1. 



presented by the well-known toy which con- 

 sists of a flat metal disk DD , Fig. 1, at the 

 end of a metal tube and a light metal disk 

 dd, which is hindered from moving sidewise 

 by a pin p which projects into the tube. 

 Blowing through the tube causes the disk dd 

 to be held tightly against the disk DD. 



Fig. 2. 



Fig. 2 shows an arrangement in which all 

 of the essential actions which enter into the 

 behavior of Tig. 1 are reproduced in a more 

 easily intelligible form. A light metal disk 

 dd is prevented from moving sidewise by a 

 pin J), and a jet of water impinging upon the 

 center of the disk dd causes it to float. The 

 thin stream of water which moves radially 

 outwards over the surface of the disk main- 

 tains a wall of water around the edge of the 



disk, and the disk floats very much as if it 

 were a shallow pan with a metal rim. Over 

 the surface of the disk the thin stream of 

 water has a high velocity and a low level 

 (pressure) and at the edge it raises itself to 

 a higher level (pressure) as it loses its velocity. 

 So, in the case of the apparatus shown in Fig. 

 1, the thin stream of air between the two 

 disks has a high velocity and a low pressure 

 and at the edge of the disks it raises itseK to 

 a higher pressure (atmospheric pressure) as 

 it loses its velocity. Evidently, then, the air 

 between the disks dd and DD of Fig. 1 is at 

 a lower pressure than the outside air and the 

 difference in pressure operates to hold the 

 disks together. W. S. Fraxklix. 



THE FIRST DISCO^"ERT OF FOSSIL SEALS IX 

 AMERICA. 



To THE Editor of Sciexce: While engaged 

 in collecting fossils for the National Museum 

 from the northern range of the Calvert Cliffs, 

 on the west shore of Chesapeake Bay, Mary- 

 land, during the summer and fall of 1905, I 

 had the good fortune to find bones of true 

 seals, which are, so far as I am aware, the 

 first authentic remains of American fossil 

 seals. As the Calvert Cliffs are entirely 

 Miocene at their northern end, these bones 

 can safely be assig-ned to that geological 

 period. They will be described later in the 

 Proceedings of the Xational Museum. 



Remains from several localities in the 

 United States, supposed to be those of seals, 

 have been described or alluded to by Leidy 

 and other writers, but, as shown by Dr. Allen's 

 careful review, they are all of doubtful au- 

 thenticity, ' not a single extinct species having 

 been certainly determined.' F. W. True. 



U. S. National Ml'Seum, 

 Washixgtox, D. C, 

 November 23, 1905. 



a blazixg beach. 

 Ix the early part of September the papers 

 throughout the country gave wide publicity to 

 the occurrence of a phenomenon at Eittery 

 Point, Me., which attracted much local con- 

 sideration because of its sensational aspects, 

 and which might be correctly described as a 



