339 
only three small ponds have remained, the largest of them being 
hardly one mile and a half wide. The drying up has been 
going on with remarkable rapidity. Even twenty-five years 
ago there were several lakes ten and eight miles long and wide, 
where there are now but little ponds. Lake [chebakly, which 
was represented in 1784 as an oval forty miles long and thirty 
miles wide, has an elongated irregular shape on the map of the 
beginning of our century ; it measures, however, still forty miles 
in length, and its width varies fron seven to twenty miles; 
while several small lakes to the east of it show its former extension. 
Thirty years later we find in the same place but a few small 
lakes, the largest of which hardly has a length and width of 
three miles; and now, three small ponds, the largest of them 
having a width of less than two miles, are all that remain of 
a lake which covered about 350 square miles a hundred years ago. 
The same process is going on throughout the lakes of West 
Siberia, and throughout the Aral-Caspian depression, No 
geologist doubted upon, but we cannot but heartily thank M. 
Yadrintseff for having published documents which permit to 
estimate the rapidity of the process. pak. 
UNIVERSITY AND EDUCATIONAL 
INTELLIGENCE 
WE understand that Mr. Granville Cole has been appointed 
to the Professorship of Geology at the Bedford College, London, 
and Miss C, A. Raisin to the Demonstratorship in Botany at 
the same institution. 
SCIENTIFIC SERIALS 
THE Fournal of Botany.—The number for July commences 
with the first part of an important article (illustrated), by Messrs. 
Roy and Bisset, on Japanese Desmids, chiefly obtained from a 
lake in the Island of Yesso. The majority of the forms obtained 
are cosmopolitan, but some of them of great rarity in Europe. 
There are also some new species. Papers follow on British 
Rubi, on the Rubi of Somersetshire, and on the flora of St. 
Kilda. 
American Fournal of Science, July.—Memorial of Edward 
Tuckerman, by Asa Gray. This botanist, who was born in 
Boston, December 7, 1817, and died March 15, 1886, was dis- 
tinguished especially in the field of lichenology, to which he 
devoted most of his life. He was the author of a ‘‘ Synopsis of 
the Lichens of New England, the other Northern States, and 
British America,” of ‘‘Lichenes Americ Septentrionalis 
exsiccati” (3 vols.), and many other papers on this branch of 
botany, in which he has left behind him no superior.—Notes on 
American earthquakes (No. 15), by Prof. C. G. Rockwood, jun. 
This fifteenth paper of the series gives a summary of such infor- 
mation as the author has been able to gather on the earthquakes 
of North and South America during the year 1885. It tabulates 
seventy-one shocks, classed according to their intensity as very 
light, light, moderate, strong, severe, or destructive. Of these 
as many as thirty-four occurred on the Pacific coast of the 
United States, where the Bay of San Francisco appears to be a 
chief centre of seismic disturbance.—Observations on the 
Tertiary and Grand Gulf of Mississippi, by Dr. Otto Meyer. 
The author finds no place where Grand Gulf strata overlie the 
Marine Tertiary, although there are two districts where strata 
undistinguishable from unquestioned Grand Gulf are overlain by 
Marine Tertiary. The Grand Gulf is not, generally speaking, 
a marine formation, for it contains fresh-water shells. In 
Eastern Mississippi occurs a thick and extended marine green- 
sand formation parallel to the strata immediately below the 
Claiborne profile. Its fauna is Claibornian, but approaches 
the Jacksonian.—Notes on the volcanic rocks of the Re- 
public of Salvador, Central America, by Arnold Hague and 
Joseph P. Iddings. This study is based on specimens gathered 
by Mr. W. A. Goodyear in the course of his explorations in 
Salvador. They are of a highly diversified character, ranging 
from very basic to highly acidic forms, from rocks rich in 
olivine to others abounding in quartz, and may be classified 
under the heads of basalt, pyroxene-andesite, hornblende-pyro- 
xene-andesite, hornblende-mica-andesite, dacite, and possibly 
rhyolite, basalt and dacite being best represented. Nearly all have 
their counterpart in Nevada, although there occur many varieties 
in Nevada not found in the limited series from Salvador.— 
The genus Strephochetus: di-tribution and species, by Henry 
NATURE 
[| August 5, 1886 
M. Seely. Since reporting last fyear the presence of the fossil 
sponge, Strephochetus occellatus, at one or two places in Vermont 
and New York, the author has traced it to many other districts 
in those States. To the type of the genus, S. occel/atus, he now 
also adds three new species—S. drainerdi, S. atratus, and S. 
richmondensis.—Preliminary report on the geology of the Cobs- 
cook Bay district, Maine, by N. S. Shaler. This paper, pub- 
lished by permission of the Director of the U.S. Geological 
Survey, gives a portion of the general results of two months’ 
exploring work on the shore-line of Cobscook Bay during the 
summer of 1884. 
as throwing light on the position of the shore-line in past times. 
A conglomerate apparently of the Clinton or Niagara age on 
the west side of South Bay seems to show that the shore in 
this district was not far away during a portion of the time when 
the Cobscook series was forming. In the age of the Perry sec- 
tion there is also evidence that the coast was near its present 
position and that the rocks exposed to erosion were chiefly of 
The fossiliferous strata have a special interest 
A 
6 
4 
the Laurentian epoch.—On the well-sperometer, by Alfred M, — 
Meyer. 
tions, has for the last ten years been used by the author in his 
laboratory for the purpose of measuring the radius of curvature 
of a lens of any linear aperture.—On some general terms applied — 
to metamorphism and to the porphyritic structure of rocks, by 
James D. Dana. The three recognised forms of metamorphism 
are described and characterised as‘(t) crystallinic ; (2) para- 
morphic ; (3) metachemic. A full terminology of porphyritic 
varieties is given, based in plan on such terms as orthophyre, 
augitophyre, &c. 
Bulletin de ? Académie Royale de Belgique, May.—On the 
transparency of platina, by Ed. van Aubel. After ascertaining 
by experiment that a sheet of cobalt, iron, or nickel obtained by 
electrolysis on a transparent sheet of silver, is not really trans- 5 
parent, as is now generally assumed, the author here endeavours — 
to settle the question as regards mirrors of platina chemically 
produced, that is, by a deposit of platina on a sheet of glass, and 
the transparency of which is admitted by Kundt. Working 
witha large mirrorsupplied by Paul Lohmannof Berlin, from whom 
Kundt also obtained those used by him, M. van Aubel found, 
by means of spectroscopic observations, that the metal of these 
mirrors is not really transparent, the light merely filtering 
through the interstices left between the particles of platina de- — 
posited on the surface.—A contribution to the study of the salts 
of platina, by M. Eugéne Prost. The author deals especially 
with the action of nitric acid and of perchloric acid on platinic 
hydrate, and with the action of nitric acid on the precipitated 
bisulphuret of platina, his object being to form the so-called 
normal platinic nitrates, perchlorates, and sulphates. Failing to 
obtain these substances, he endeavoured to get double salts of 
normal composition by combining them with alkaline salts 
having corresponding acids. The results show that all the com- 
pounds thus obtained still correspond with basic platinic salts, — 
so that it would so far appear that a normal platinic nitrate can- 
not be obtained.—On the unstable equilibrium of the surface- 
layer of a fluid, by G. van der Mensbrugghe. 
stability of surface-layers exposed to the free action of the atmo- 
sphere is demonstrated on theoretical grounds. From this~ 
theory the author proposes in another paper to deduce the exist- 
ence of superficial tension on the free surface of a fluid, or on 
the surface common to two fluids, or to a fluid and solid, thence 
deriving a rational explanation of the phenomenon of evapora- 
tion.—On the heat of the alloys of lead and tin, by W. Spring. 
Continuing the researches of Ermann, Rudberg, Regnault, 
Wiedmann, and others, the author seeks to determine for re- 
stricted intervals of temperature the total heat of these alloys 
relatively to that of their constituents. Further light is thus 
thrown both on the constitution of these bodies, and on the 
question why their point of fusion is lower than that of their 
constituents. 
Rendiconti del Reale Istituto Lombardo, June.—On some un- 
conscious intervals in a co-ordinate series of psychic acts, by 
Tito Vignoli. The object of this essay is to ascertain experi- 
mentally whether in the co-ordinate exercise, or logical sequence, 
of thought, it sometimes happens that some of the connecting 
links of the argument are supplied unconsciously. Several in- 
stances are quoted, together with the author’s personal expe- — 
rience, showing that this really is the case. It is incidentally 
argued that, in its complexity, the brain is a large organ of com- 
pensation, so that, if any of its parts in which special functions 
are localised become disturbed or injured, these may, within 
The absolute in- — 
The instrument here described, with numerous illustra- 
