State of the Interior of the Earth. 215 



January 10, 1839. — A paper was read, entitled, "On the Laws 

 of Mortality." By Charles Jellicoe, Esq. Communicated by P. 

 M. Roget, "M.D., Sec. R.S. 



The author, considering that the variations and discrepancies in 

 the annual decrements of life which are exhibited in the tables of 

 mortality hitherto published would jDrobably disappear, and that 

 these decrements would follow a perfectly regular and uniform law, 

 if the obsen'ations on which they are founded were sufficiently nu- 

 merous, endeavours to arrive at an approximation to such a law, by 

 proper interpolations in the series of the numbers of persons living 

 at every tenth year of human life. The method he proposes, for 

 the attainment of this object, is that of taking, by proper formulae, 

 the successive orders of differences, until the last order either disap- 

 pears, or may be assumed equal to zero. With the aid of such dif- 

 ferences, of which, by applying these formulae, he gives the calcula- 

 tion, he constructs tables of the annual decrements founded princi- 

 pally on the results of the experience of the Equitable Assurance 

 Society. 



January 17. — A paper was read, entitled, " On the state of the 

 Interior of the Earth." By W. Hopkins, Esq. A.M., F.R.S., Second 

 Memoir. " On the Phenomena of Precession and Nutation, assuming 

 the Fluidity of the Interior of the Earth*." 



In tliis memoir the author investigates the amount of the luni- 

 solar precession and nutation, assuming the earth to consist of a 

 solid spheroidal shell filled with fluid. For the purpose of present- 

 ing the problem under its most simple form, he first supposes the 

 solid shell to be bounded by a determinate inner spheroidal surface, 

 of which the ellipticity is equal to that of the outer surface ; the 

 change from the solidity of the shell to the fluidity of the included 

 mass being, not gradual, but abrupt. He also here supposes both 

 the shell and the fluid to be homogeneous, and of equal density. 

 The author then gives the statement of the problem which he pro- 

 poses to investigate ; the investigation itself, which occupies the re- 

 mainder of the paper, being wholly analytical, and insusceptible of 

 abridgement. The following, however, are the results to which he 

 is conducted by this laborious process : namely, that, on the hypo- 

 thesis above stated, 1 . The Precession will be the same, whatever be 

 the thickness of the shell, as if the whole earth were homogeneous 

 and solid. 2. The Lunar Nutation will be the same as for the homo- 

 geneous spheroid to such a degree of approximation that the diff"er- 

 ence would be inappreciable to observation. 3. The Solar Nutation 

 will be sensibly the same as for the homogeneous spheroid, unless 

 the thickness of the shell be very nearly of a certain value, namely, 

 sometliing less than one quarter of the earth's radius ; in which case 

 this nutation might become much greater than for the solid spheroid. 

 4. In addition to the above motions of precession and nutation, the 

 pole of the earth' would have a small circular motion, depending en- 

 tirely on the internal fluidity. The radius of the circle thus de- 



* An abstract of Mr. Hopkins's First Memoir will be found in our 

 Number for January, pres. vol. p. 52. — Edit. 



