; 
ance of a given nickel wire with temperature is greater, on the 
average, than the corresponding quantity for platinum or palla- 
dium, and less than that for iron. (2) The ‘‘logarithmic rate” 
—that is, the rate of change per unit rise of temperature of unit 
resistance at any temperature—falls off more slowly for nickel 
as the temperature rises to 200° C. than for platinum or palla- 
dium. (3) At about 200° C. the rate of resistance growth for 
nickel increases markedly, and continues practically steady, till 
about 320° C., when a sudden decrease occurs, and thereafter 
the resistance steadily increases at this diminished rate. In 
other words, between the limits of temperature specified, the 
slope of the resistance curve is much steeper than for any 
other. The same peculiarity is probably possessed by iron 
between the temperatures of a dull red and a bright red 
heat. (4) The peculiarity occurs (in each case) between 
the limits of temperature within which the striking thermo-elec- 
tric peculiarity discovered by Tait also occurs. This peculiarity, 
which is most briefly described as an abrupt change in the 
sign of the Thomson effect, is not known to be possessed by any 
other metal. (5) There is thus a strong presumption that the 
Thomson effect in metals has a close connection with the mutual 
relations of resistance and temperature—at any rate in metals in 
which the Thomson effect is proportional to the absolute tem- 
perature (according to Tait’s theory) the “logarithmic rate” of 
change of resistance seems to be very approximately inversely as 
the absolute temperature. In nickel and iron, in which the law 
of the Thomson effect is peculiar, such a simple relation between 
resistance and temperature does not hold.—Prof. Tait discussed 
the effect of external forces on a system of colliding spheres. He 
gave a proof, much more simple than Maxwell’s, of the fact that 
gravity has no effect in altering a uniform distribution of tem- 
perature throughout a yertical gaseous column. His proof is 
founded on the assumption that, in a horizontal layer of gas 
which has arrived at a steady state, all particles passing across 
the upper surface do so on the whole as if they had freely passed 
through the layer.—Dr. John Murray read a paper by Dr. H. B. 
Guppy on the mode of formation of the coral reefs of the 
Solomon Islands. In this paper the typical reefs were described 
with the various corals growing on them. In places exposed to 
the full sweep of the trade-winds the corals do not grow higher 
than to about 7 or ro feet from the surface. In sheltered places 
they are found at a depth of from 4 to 5 feet. Dr. Guppy 
believes that the reefs never ri-e to the surface without upheaval. 
He gives a theory of the construction of barrier reefs, which 
corresponds to that formerly given by Le Comte to explain the 
reefs of Florida.—Mr. J. T. Cunningham, of the Scottish Marine 
Station, read a paper on the eggs and early stages of some 
teleosteans, and also a paper on the reproductive organs of 
Baellostoma, and a teleostean egg from the West Coast of 
Africa.—Mr. Patrick Geddes gave a synthetic outline of the 
history of biology, and also read a paper on the theory of growth, 
reproduction, heredity, and sex. 
SYDNEY 
Linnean Society of New South Wales, May 26.—Prof. 
W. J: Stephens, M.A., F.G.S., in the chair.—The following 
papers were read :—Notes on some Australian Tertiary fossils, 
by Capt. F. W. Hutton. In this paper, which is based on the 
examination of a fine collection of Australian Tertiary fossils 
recently sent to the Canterbury Museum by Prof. Tate of Ade- 
laide, Capt. Hutton enumerates seventeen species of molluscs 
and echinoderms which are common to the Tertiary strata both 
of Australia and New Zealand, and deals with their synonymy. 
—On some further evidences of glaciation in the Australian 
Alps, by James Stirling, F.L.S., communicated by C. S. 
Wilkinson, F.G.S. After reviewing what has been written on 
the subject of glacial action in Australia, the author adduces 
fresh evidence in favour of such action, obtained by himself and 
Dr. Lendenfeld during a recent visit to Mount Bogong, the 
highest mountain in Victoria, where erratics, perched blocks, 
smoothed surfaces, and old moraines were met with.—Jottings 
from the Biological Laboratory, Sydney University, by W. A. 
Haswell, M.A.: (No. 7) On a method of cutting sections of 
delicate vegetable structures ; (No. 8) on the vocal organs of 
the Cicada.—Mount Wilson and its ferns, by P, N. Trebeck. 
Mr. Trebeck describes the position, geology, soil, and vegeta- 
tion generally of Mount Wilson, and gives details of 15 genera 
of ferns, including 38 species, which were growing there in the 
_ greatest luxuriance from the very summit to a considerable dis- 
397 
tance down the slopes and gullies of the mountain.—List of the 
Rhizopoda of New South Wales, by Thomas Whitelegge. The 
list contains 24 species, with exact localities, and notes on col- 
lecting, preserving, and mounting Rhizopods. ‘The species are 
mostly identical with those found in Europe, America, and 
India. Amongst those of interest the following may be men- 
tioned :—Arcella dentata, Ehr., Pelomyxa palustris, Greeff, 
Raphidiophrys elegans, Hert. and Less., Clathrulina elegans, 
Ceinkowski, and Aiomyxa vagans, Leidy. 
PARIS 
Academy of Sciences, July 19.—M. Jurien de la Gravieére, 
President, in the chair.—Remarks accompanying the presenta- 
tion of M. de Saint-Venant’s important manuscript memoir on 
‘the resistance of fluids,” by M. Boussinesq. This unpublished 
work, begun in 1847, and not completed till the year 1885, a 
short time before the author’s death, embodies historical, 
physical, and practical considerations regarding the problem of 
the mutual dynamic action of a fluid and a solid, especially in 
the state of permanence supposed to be acquired by their move- 
ments. It comprises three parts, the first dealing with the 
researches of previous physicists on the impulse of fluids in 
motion on solil bodies encountered by them ; the second show- 
ing theoretically that this impulse is connected exclusively with 
the ‘‘imperfection of the fluid,” that is, the development of 
friction, which to be surmounted requires a higher pressure on 
the upper than on the lower surface of the submerged body ; the 
third containing a practical calculation of the impulse experienced 
by a body in any indefinite fluid current.—On the displacement 
of ammonia by other bases, and on its quantitative analysis, by 
MM. Perthelot and André. It is shown that in the presence of 
soda the double salts yield their ammonia far less readily than 
the sal ammoniacs unassociated with another base ; also that in 
the ordinary conditions of analyses magnesia is powerless to 
entirely displace the ammonia. With certain salts, such as 
ammoniaco-magnesian phosphate, the displacement is extremely 
slight or nil. These results must henceforth be taken into 
account in the analysis of earths and of other products contain- 
ing organic matter associated with the phosphates or with mag- 
nesia.—On a reindeer’s antler embellished with carvings found 
by M. Eugene Paignon at Montgaudier, by M. Albert 
Gaudry. This relic of the reindeer age ranks among the most 
interesting animal and human remains in recent years discovered 
by M. Paignon in the Montgaudier Caves, Tardoire Valley, 
Charente. It is pierced with a large hole and covered with 
carvings executed with such a sure hand and sentiment of form 
that it shows even to greater advantage under the magnifying 
glass than when viewed with the naked eye. One face shows 
two seals (Phoca vitulina and a larger perhaps of different spe- 
cies), a fish (a salmon or trout), and three twigs of plants. On 
the other side are two long slender animals, apparently eels, 
three other animal figures exactly alike but indeterminable, and 
an insect. This specimen of prehistoric art, of the authenticity 
of which there can be no doubt, has been presented by the 
finder to the Museum, together with several other objects from 
his valuable collection.—On the real position to be assigned to 
the fossil flora of Aix in Provence (continued), by M. G. de 
Saporta. The conclusion already arrived at on stratigraphic 
grounds, that this flora belongs to the triple series of the Upper 
Eocene, Tongrian, and Aquitanian, is here confirmed by the 
Palzeontological indications themselves.—On the development in 
series of the potential of a homogeneous revolving body, by M. 
O. Callandreau.—On the variations of the absorption-spectra in 
non-isotropic mediums, by M. Henry Becquerel. Apart from 
certain anomalies here described, it may be generally assumed 
that for each absorption-band there is a single system of three 
principal rectangular directions, of such a nature that the in- 
tensity of a luminous vibration proceeding from a crystal parallel 
to the direction of the incidental vibration may be represented 
by the form 7 = (a cos? a + 4 cos*B + ¢ cos *y)?, where a, 8, 
indicate the angles of direction of the vibration with the principal 
directions, and 2”, 62, c? the principal intensity of the radiation in 
question. This hypothesis seems to be confirmed by photometric 
measurements executed with plates of epidote.—On the decom- 
position of hydrofluoric acid by an electric current, by M. H. 
Moissan.—Note on urethane regarded from the standpoint of 
chemical analysis by M. Georges Jacquemin.—Action of some or- 
ganic chlorides on diphenyl in the presence of the chloride of alu- 
| minium, by M. P. Adam.—Gn the normal propylamines, by M. 
