JANUARY 11, 1884.| 
taining a brief résumé of the principal char- 
acteristics of the period, together with a short 
account of the progress made during the period 
in each of the branches of the mathematical sci- 
ence of the time, — geometry, arithmetic, phys- 
ics, and astronomy. ‘This is followed by the 
biographies of the mathematicians and physi- 
cists of the period and an analysis of their 
work. 
The three introductory chapters, taken to- 
gether, form a short and interesting history of 
Greek mathematics ; while the biographies are 
sufficiently full, and the analyses are remarka- 
_ bly clear and concise. 
SECONDARY BATTERIES. 
The chemistry of the secondary batteries of Plante and 
Faure. By J. H. Guapstone and ALFRED 
Trise. London, Macmillan & Co., 1883. (Na- 
ture series.) 11+59p. 16°. 
Tue valuable papers.of Gladstone and Tribe, 
originally printed in Nature, have been pub- 
lished in a collected form in the present volume, 
which contains much information as to the 
chemical actions going on in the Planté and 
Faure batteries. In successive chapters the 
authors consider the subjects of local action, 
SCIENCE. 
a1 
the chemical changes occurring in the charge 
and discharge of the cell, the function of the 
sulphate of lead formed, and some minor top- 
ics. The chapter devoted to the function of 
the sulphate of lead, which the authors have 
shown to be formed in the normal action of 
the battery, is especially interesting. In the 
formation of a Faure cell, sulphate of lead, 
originally produced by local action, is oxidated 
to a peroxide on one plate, and reduced to 
spongy metallic lead on the other; and, when 
the cell is discharged, lead sulphate is finally 
produced on both plates. On recharging the 
battery, the authors consider that the lead sul- 
phate is again oxidated on one plate, and 
reduced on the other, as when the cell was 
originally formed, —a point which is a very 
practical one, as the lead sulphate, if not oxi- 
dated, will soon prove fatal to the usefulness of 
the cell. This view, announced in the original 
papers, is substantiated by a number of recent 
experiments, notwithstanding the doubts that 
have been thrown upon it; so that, in charging 
and recharging, the plate of the cell is not 
corroded. It is also shown that the fact 
noticed by Planté, that elevation of tempera- 
ture facilitates the formation of the cell, is 
explained by the more rapid formation of lead 
sulphate under these conditions. 
RECENT PROCEEDIN GS OF SCIENTIFIC SOCIETIES. 
Vassar brothers’ institute, Poughkeepsie. 
Dec. 5.— Professor W. B. Dwight gave the results 
of a recent re-examination by himself of Van Duzer’s 
iron-mine, Cornwall station, Orange county, N.Y. 
Here a low ridge presents a red rock of sandstone and 
conglomerate, running into red shales to the south, 
in contact conformably with a highly fossiliferous 
limestone in nearly vertical layers. No other com- 
bination of the kind is apparent in this region, and 
there was much speculation among early geologists 
as to the horizon. W. B. Rogers called the red rock 
the triassico-jurassic sandstone; Dr. W. Horton con- 
sidered it the Medina group, and assigned the lime- 
stone some place lower; Prof. Mather, with some 
doubt, concurred with Horton, and further assigned 
the limestone to the Catskill shaly limestone. Prof. 
Dwight, after a careful study of the locality, is satis- 
fied that the red rocks are of the Medina epoch, and 
the limestones lower Helderberg; but by the fossils 
' he identifies, in addition to the Catskill shaly lime- 
stone, the tentaculite limestone and the lower pen- 
tamerous groups. He finds no foundation for the 
statements of Horton, indorsed by Mather, that the 
iron ore occurs in layers between the layers of lime- 
stone. On the other hand, it is a bed of limonite 
formed at the base of the ridge superficially, as in 
other iron-mines of the region, by the decomposition 
of the red ferruginous shales at the junction with the 
limestone. 
Five hundred and sixty-two specimens, represent- 
ing various departments of natural history and 
archeology, were reported to the museum by the 
secretary. 
Franklin institute, Philadelphia. 
December 19.— A special committee, appointed to 
consider the propriety of recommending the councils of 
the city of Philadelphia to pass an ordinance requir- 
ing steam-engineers to pass an examination and to 
be provided with a license, as evidence of their com- 
petency, made majority and minority reports; the 
first taking the view that such action on the part of 
the society would be inexpedient, and the latter 
recommending such action. The reports were freely 
discussed, pro and con; and the subject was post- 
poned for final action until the stated meeting in 
January. 
Mr. G. Morgan Eldridge then read a paper on ‘ The 
British patent designs and trade-marks act of 1883 
as affecting American inventors,’ explaining the pro- 
visions of the new law to go into operation on the 1st 
