300 Catalogue Raisonn4. 



This little book is in reality the only philosophical and precise original in- 

 troduction to botany in the English language 5 but it is, after all, only 

 an outline, and we trust the author will lose no time in iilling it up, and 

 giving it tnat air of importance, in the eye of the public, which it justly 

 merits. 



Letter relating to the Figure of the Earth. By James Ivory, 

 Esq. M.A. F.R.S. Sec— Phil. Mag. April 1830. 



Mr. Ivory writes this letter as a statement of what he has contributed to 

 the theory of the figure of the earth, and to assert his claim to his pe- 

 culiar notions. 



He considers himself to have demonstrated the insufficiency of Clairault's 

 theory, by showing that it inadvertently neglects the attraction between 

 certain portions of an homogeneous planet, supposed fluid : and by this 

 means omits to take into account pressures prevailing in the interior of 

 the mass, and vanishing at the surface, which cannot but have an influ- 

 ence on the figure of equilibrium ; and further states, that he gave the 

 true conditions for the equilibrium of a homogeneous planet in a fluid 

 state, deduced a priori from the principle of hydrostatics, without ne- 

 glecting any cause tending to change the figure of the fluid, in the Phil. 

 Trans, for 1824. 



It is now well known that the equation given by Maclaurin, of the sur- 

 face of a spheroid, (supposing that a fluid homogeneous planet is in equi- 

 librium when it has the figure of an oblate elliptical spheroid of revo- 

 lution,) has two different solutions. To account for the existence of 

 two figures of equilibrium which would result from this equation, Mr. 

 Ivory examined the forces in action in the interior of the mass, and 

 found that two different sets of surfaces may be traced within the fluid, 

 each of which is possessed of the property of the level surfaces in Clai- 

 rault's theory, that is, the intensity of pressure is the same at all these 

 points. The two sets of interior surfaces have difl^erent relations to the 

 outer surface, and one set only can properly be called level surfaces. 



Lastly, Clairault resolved the problem a long time ago with respect to the 

 equilibrium as applied to a heterogeneous fluid, but retained only the 

 first power of the eUipticity. Mr. Ivory states himself to have publish- 

 ed, in the Phil. Mag. for July 1826, a solution which takes in the second 

 I power of the oblateness, by a method which may be extended to any 

 power of the same. 



Linnaea, a Botanical Journal. By Dr. D. F. L. Schlechten- 

 DAL, July and October 1829. 8vo. Berlin. 



These two numbers contain, amongst other papers ; 1st, the continuation 

 of the description and classification of the Synantherm of the Herbarium 

 of Berlin, by F. Lessing ; 2. a review of the HepaticcB of the Cape, by 

 Lehmann ; 3. remarks on the Cratcegus and Rumex of the flora of Ger. 

 many, by Fingerhuth ; 4. descriptions of new or rare cryptogamous 

 plants, {Cceeoma, UredOy'j by Fr. Rudolphi ; 5. new genera of phaneroga- 

 mous plants, by Hemprich and Ehrenberg ; 6. varieties or hybrids of 

 indigenous plants, by Lasch ; 7- an enumeration of mushrooms {Hyme- 

 nomyceti pileati) recently found in the march of Brandenburg, by Leasch ; 

 8. a general view of the flora of Mexico, by M. Schiede. 



Zeitschrift fur Physiologic, Gazette of Physiology. By Tiede- 

 MANN and Tkeviranus. Vol. III. Part 2. 1829. 



This Part contains, amongst other memoirs ; 1. anatomy of the ^joArodi^a 

 aculeata, Lin. by G. R. Tr^viranus; 2. on tlie fractures of bones, and 

 the sutures which they form, by S. Th. de Soemmering ; 3, on the for- 

 mation of neuters in the Hymenoptera, and principally in bees, by G. R. 



