110 Dr. W. Farr. English Reproduction Table. [Jan. 29, 



depends on the differences of JE, that is, on the diameter of the earth's 

 orbit, the determination of v cos X depends on JE itself, a mnch larger 

 quantity. 



But no method can be made available without good tables of the 

 motion of the satellites, and as I am not an astronomer, I do not know 

 whether, in comparing the observations with the tables of De Damoi- 

 seau, any attempt has been made to consider the term in v cos A. 



I have, therefore, taken the liberty of writing to yon, as the matter 

 is beyond the reach of anyone who has not made a special study of 

 the satellites. 



In the article E [ether] in the ninth edition of the " Encyclopaedia 

 Britannica," I have collected all the facts I know about the relative 

 motion of the ether and the bodies which move in it, and have shown 

 that nothing can be inferred about this relative motion from any 

 phenomena hitherto observed, except the eclipses, &c, of the satellites 

 of a planet, the more distant the better. 



If you know of any work done in this direction, either by yourself 

 or others, I should esteem it a favour to be told of it. 



Believe me, 



Yours faithfully, 

 (Signed) J. Clerk Maxwell. 



D. P. Todd, Esq. 



January 29, 1880. 

 THE PRESIDENT in the Chair. 



The Presents received were laid on the table, and thanks ordered 

 for them. 



The following Papers were read : — 



I. "English Reproduction Table." By Dr. W. Farr, F.R.S. 

 Received January 15, 1880. 



(Abstract.) 



This table is a development of the English Life Table, from which 

 the fundamental columns of ly and Vy are taken, and is intended to 

 show the constitution of the female population, as regards married and 

 unmarried, and the reproductive power at the several ages. 



The female population, Ty, is divided into married (uxores) 

 unmarried (filiee), and widowed (viduse), according to the propor- 

 tions of these classes of the various ages at the census of 1871 ; thus, 

 of a total of 14,936,770, aged 15 and upwards, 7,957,456 are wives, 

 4,660,311 are spinsters, 2,319,003 are widows. 



