1888.] 



Presents, 



117 



2. In the case of the perissads (the elements of uneven atomicity) 

 the complete curve which includes their perturbations from the central 

 curve is — 



7i r / i • m7r i • mir i . \~1 



y m = h log |j*^m 4- 5" sin-- + ^ sin -jg- -f subsequent terms^ J, 



the next term being probably either — 



— | sin — , or - f sin — ■ 



3. The form of the function representing the perturbations of the 

 artiads is different, at all events after the third term. 



Section 3. — There are other neighbouring logarithmic curves which 

 pursue a course close to the observed positions, and in Section 3 the 

 method adopted in dealing with these curves is described, and the 

 grounds on which they have been successively excluded are stated. 

 The evidence relied on has been, for the most part, that the perturba- 

 tions from them are less reducible to order. 



In Section 4 the curve finally selected is thrown into a polar form, 

 and furnishes a diagram of singular convenience for laboratory use. 

 It presents conspicuously the information which a Newlands and 

 Mendelejeff 's table is capable of supplying, with the further advan- 

 tage of also placing before the eye an intelligible representation of 

 the atomic weights. 



The last section contains some observations suggested by the inves- 

 tigation. 



Presents, April 19, 1888. 



Transactions. 



Baltimore : — Johns Hopkins University. Circular. Vol. VII. 



No. 64. 4to. Baltimore 1888. The University. 



Berlin : — K. P. Akademie der Wissenschaf ten. Sitzungsberichte. 



1887. Hefte 40-54. 8vo. Berlin. The Academy. 



Calcutta: — Asiatic Society of Bengal. Journal (Natural History). 



Vol. LVI. Part 2. Nos. 2-3. Ditto (Philology). Vol. LVI. 



Part 1. Nos. 2-3. 8vo. Calcutta 1887 ; Proceedings. 1887. 



Nos. 9-10. 1888. No. 1. 8vo. Calcutta. The Society. 



Cambridge, Mass. : — Harvard College. Museum of Comparative 



Zoology. Bulletin. Vol. XIII. No. 7. 8vo. Cambridge 1888. 



The Museum. 



Cherbourg : — Societe Nationale des Sciences Naturelles et Matbe- 

 matiques. Memoires. Tome XXV. 8vo. Paris 1887. 



The Society. 



