Royal Society. 421 
can never cut it in more than two. He remarks, however, that if 
we could conceive two poles of like kinds to exist without any other 
whatsoever, we might have either four points of verticity, or only 
two, according to circumstances ; but he waves the discussion of this 
particular case, as being irrelevant to the purpose of his present 
inquiry. 
Mr. Davies announces his intention of shortly laying before the 
Society a continuation of these researches; devoting the next series 
to the points of maximum intensity. 
“ Memoir on the Metamorphoses in the Macroura, or Long- 
tailed Crustacea, exemplified in the Prawn (Palemon serratus).” By 
John V.Thompson, Esq.,F.L.S., Deputy Inspector-General of Hospi- 
tals. Communicated by Sir James Macgrigor, M.D., F.R.S., &c. 
Theauthor gives descriptions, illustrated by outline figures, of three 
different stages of growth of the Prawn; the first being that of the 
larva immediately on its exclusion from the egg ; the second, at a 
later period, when it has acquired an additional pair of cleft mem- 
bers, and a pair of scales on each side of the tail ; and the third, at 
a still more advanced stage of development, when it presents the 
general appearance of the adult Prawn, but still retains the natatory 
division of the members, now increased to six pair. The author 
thinks it probable that an intermediate stage of metamorphosis exists 
between the two last of these observed conditions of the animal. 
Feb. 11.—A paper was in part read, entitled, “ On Voltaic Com- 
binations.” Ina letter addressed to Michael Faraday, Esq., D.C.L., 
F.R.S. Fullerian Professor of Chemistry in the Royal Institution of 
Great Britain, &c., &c. By John Frederick Daniell, Esq., F.R.S., 
Professor of Chemistry in King’s College, London. 
Feb. 18.—The reading of Mr. Daniell’s paper, entitled, “ On Vol- 
taic Combinations,” in a letter to Michael Faraday, Esq., D.C.L., 
F.R.S., &c., was resumed and concluded. 
The author, after expressing his obligations to Mr. Faraday for 
the important light which hislate researches in electricityhave thrown 
on chemical science*, proceeds to state that in pursuing the train of 
inquiry which has thus been opened, he has obtained further confir- 
mations of the truth of that great principle discovered and esta- 
blished by Mr. Faraday, namely, the definite chemical action of 
electricity ; and has thence been led to the construction of a voltaic 
arrangement which furnishes a constant current of electricity for 
any required length of time. 
For the purpose of ascertaining the influence exerted by the dif- 
ferent parts of the voltaic battery in their various forms of combi- 
* The greater part of Mr. Faraday’s Experimental Researches in Elec- 
tricity will be found entire in Lond. and Edinb. Phil. Mag., vol. iii., vol. v., 
vol. vi.; and of his other Series abstracts have been given in Phil. Mag. and 
Annals, N.S., vol. xi., and in the succeeding volumes of Lond. and Edinb. 
Phil. Mag. Mr. Faraday’s Seventh Series, on the definite chemical action 
of Electricity, appeared in Lond. and Edinb. Phil. Mag., vol. v. p. 161; and 
his Tenth Series, on the construction of the Voltaic Battery, in our present 
volume, p. 114,—Eprr. 
