1872.] 



Researches on Solar Physics. 



289 



writer's observations indicate that the former substance is more stable than 

 the latter, which rapidly becomes more or less coloured ; not improbably 

 these two forms are polymerides, the first being C 21 H 26 N 2 Oy + H 2 O, 

 the second (C )0 H l3 N0 3 ) n wH 2 O. Opianic acid*, on heating, furnishes an 

 anhydride of formula C 40 H 33 19 ; this tends to show that the formula of 

 this acid is not less than C 20 H 20 O 10 ; not impossibly, therefore, the formula 

 of narcotine may be double that usually ascribed to it, and the dimethyl- 

 nornarcotine, methylnornarcotine, and nornarcotine of Matthiessen may 

 be derivatives not of ordinary narcotine, but of its polymerides. 



The different modifications of the cinchona alkaloids are not impos- 

 sibly polymerides of one another. 



The Table (p. 288) exhibits the principal differences between codeia 

 and the polymerides above described. 



II. " Researches on Solar Physics." — III. By Warren De La 

 Rue, D.C.L., F.R.S., Balfour Stewart, LL.T)., F.R.S., and 

 Benjamin Loewy, F.R.A.S. Received March 12, 1872. 



(Abstract.) 



The authors present in this paper the third instalment of the determina- 

 tion of the areas and heliographic positions occupied by the sun-spots ob- 

 served by the Kew photoheliograph, comprising the years 1867, 1868, and 

 1869. They announce that the fourth and last instalment is in active 

 progress, and will be preceded by the final discussion of the whole ten- 

 yearly period, during which the photoheliograph has been at work. 

 This final discussion will contain the determination of the astronomical 

 elements of the sun on the basis of photographic observations ; and this 

 work, they anticipate, will not only settle the question of rotation for a con- 

 siderable time to come, but will also throw light upon many points which 

 have only recently been brought under the consideration of scientific men. 

 The results in general, they believe, will prove the superiority of photo- 

 graphic sun- observations over previous methods. The second question 

 which will be discussed is the distribution of sun-spots over the solar surface. 

 The facts already brought out indicate that the progress of the inquiry may 

 lead to some definite laws which regulate the distribution ; there appear 

 to exist centres of great activity on the sun, and the different solar meri- 

 dians seem to have various but definite intervals of rest and activity. In 

 conclusion the authors point out the necessity of devoting in future 

 greater attention to the study of the faculae, and express a hope of seeing 

 photographic sun-observations carried on in this country on a more ex- 

 tended system, connecting from day to day solar phenomena with terrestrial 

 meteorology and magnetism. 



* Proc. Roy. Soc. vol. xvii. p. 341, § III. (Mattliiessen and Wright), 



