Miscellaneous. 431 



The points wliicli Mr. Bakewell has endeavoured to establish are : 



1st. That the ordinary illustrations of the action of centrifugal 

 force, as applied to the commonly assumed figure of the earth, are 

 entirely delusive. 



2nd. That the disturbance of equilibrium by centrifugal force in a 

 fluid sphere rotating in space could not be counteracted by the ac- 

 cumulation of matter at the equator. 



3rd. That if it were possible that the matter of a fluid sphere put 

 in rotation in space could accumulate at the equator under the in- 

 fluence of centrifugal force in opposition to gravitation, it would fly 

 off altogether. 



4:th, That it loould he impossible, therefore, for a fluid mass of 

 matter rotating in space to assume the form of an oblate sjoheroid. 



5th. That it would be equally impossible for a solid spherical 

 rotating nucleus covered with water to assume that form. 



6th. That in accordance with the law of motion, that action and 

 reaction are equal and in opposite directions, a fluid mass of matter 

 rotating in space must accumulate at the poles to resist the action of 

 centrifugal force, and in the form of greatest resistance to that force. 



7th. That a prolate spheroid is the only flgure in which the 

 particles of a rotating mass of matter could adjust themselves in 

 accordance with the form of equilibrium. 



8th and lastly. That geodetic measurements, and the appearance of 

 the heavenly bodies, tend to confirm the dynamical theory, that the 

 earth is a spheroid rotating about its longest diameter. 



Notes on Atrtpa. — Mr. E. P. Whitfield has published (in the 

 19th Eeport on the New York State Cabinet) some observations on the 

 Internal Appendages of the genus Atnjpa; with a notice of the 

 discovery of a loop, connecting the spiral cones. By carefully 

 cutting and preparing favourable specimens, the author has found 

 that in place of the short crural processes so often figured, there is 

 an entire and continuous loop connecting the sjjiral cones, in a very 

 similar manner to that shown by Professor Hall to exist in his 

 genus Zygospira, but having its connection with the spiral ribbons 

 at a point relatively much nearer to their origin on the hinge-plate ; 

 still more distant, however, than the points figured by Mr. Davidson 

 and others. This loop, so far as observed, is confined to the rostral, 

 or posterior part of the shell, and never passes over or in front of the 

 spires, as in Professor Hall's genus. The author has succeeded in 

 asceiiaining the existence and form of this loop in several different 

 varieties of Atrtjpa reticularis, as well as in A. spinosa, of Hall ; and 

 he finds that in the different varieties of A. reticularis, it is subject 

 to considerable variations of form. The author furtlaer remarks, 

 that shoifld these differences prove constant in the several varieties 

 they may, when considered in connection with the differences in 

 external features, and perhaps some modifications in the form of 

 the spiral cones, serve as guides in establishing specific characters 

 in this group of shells. In a note, appended to his pajier, Mr. 

 Whitfield states that since the preparation of his paper he has ex- 



