560 
the decline of the Glacial period. On the supposition of a 
uniform rate of recession, the age of the Falls equals the length 
of the gorge divided by the annual recession; but the rate has 
been undoubtedly varied by changes in a variety of conditions, 
which must be allowed for. As thus qualified, Mr. Gilbert gave 
it as his conclusion that the maximum length of time since the 
birth of the Falls by the separation of the lakes is only 7000 
years, and that even this small measure may need significant 
reduction. 
In the Section of Chemistry, H. C. Bolton, of the Com- 
mittee on Indexing Chemical Literature, after presenting 
their report showing the large amount of valuable work 
which was being done, read a paper on the confusion which 
exists in the abbreviations employed in chemical bibliography, 
and the desirability of uniformity in designations of scientific 
periodicals. 
C. F. Mabery’s paper ‘‘On the Products of the Cowles 
Electric Furnace,” was of particular interest, and attracted 
much attention. He stated that the past year had been devoted 
more especially to the development of an increased commercial 
efficiency of the furnace, so that now 300 horse-power could by 
means of a large dynamo, be applied with greater economy in 
the results ; and by coating the charcoal employed in the furnace 
with lime, by soaking it in lime-water, the production of graph- 
ite was largely avoided, and a marked improvement in the 
working of the furnace introduced. The results—although, as 
compared to what would eventually be accomplished by electric 
smelting, they may seem crude—have reached a stage where 
their commercial success can be demonstrated. It was also 
found that when the electrodes entered the mixture in a slanting 
position the product was increased. They are now also moved 
in and out with advantage, being gradually withdrawn as the 
resistance falls. Prof. Mabery replied to the criticisms of 
Hehner of Berlin, Siemens, and others, that no new principle 
was involved, showing that the Cowles furnace is quite different 
from all hitherto constructed, and the only one of practical 
application by which a dynamo of 300 horse-power could be 
used, as by means of a resistance-box and the arrangement of 
the furnace, the sudden breaking of the current is prevented 
from burning out the dynamo. The presence of copper for the 
reduction of aluminium was shown to be unnecessary ; and, by 
complete exclusion of air from the furnace, buttons of the metal 
were easily obtained. A product which has attracted consider- 
able attention during the past year is obtained by reducing 
aluminium in presence of iron. A cast iron is formed containing 
sometimes as much as Io per cent. of aluminium, and this pro- 
duct is used to facilitate the working of crude iron, and to intro- 
duce into the various grades a small percentage of aluminium. 
In the reduction of aluminium in the presence of copper a yellow 
product is frequently taken from the furnace, which is composed 
of metallic aluminium to the extent of one-half or three-fourths, 
the balance being silicon and copper. It is also formed in the 
absence of copper, and then contains a higher percentage of 
aluminium, and always contains nitrogen. It has a resinous 
lustre, and decomposes water at 100°. 
_In the Section of Physics, Prof. T. C. Mendenhall prefaced 
his paper on “‘ Electric Thermometry ” by saying that the stric- 
tures upon the mercurial thermometer should not be carried too 
far. It has been of great value, though it may now fail to meet 
new demands. Electric thermometry is receiving especial inves- 
tigation at the Signal Office, particularly from the meteorological 
stand-point, with some promising results. Prof. Mendenhall 
reported the progress which had been made in the study of atmo- 
spheric electricity during the past year. It is not time to begin 
to think of the origin of atmospheric electricity. The problem 
is its distribution and the relation, if there be any, to weather 
changes. Some very interesting results have been reached. In 
ordinary weather the electrical condition is undergoing constant 
and rather wide variations, which are very local, as two col- 
lectors only a few feet apart may give curves differing consider- 
ably, though similar in their wider variations. When an elec- 
trical storm occurs, the curves over a wide area may be similar 
in general outline. Prof. Mendenhall also noted a phenomenon 
entirely new to him ; namely, that resistance-coils, after a current 
it passed through them for some time, upon short-circuiting will | 
yield a reverse current for hours. This phenomenon can no 
doubt be classed under the general head of polarisation, yet by 
simple polarisation it would be difficult to account for persistence ~ 
of current. This makes caution necessary in the use of resist- 
ance-coils, in order that any effects of this kind may be carefully 
NATURE 
[Oct. 7, 1886 
noted. In one instance the apparent resistance of a coil was 
found to increase fourfold when the current was reversed. 
A paper by Prof. Abbe created some discussion. The point 
of the paper was that, as the force of gravity varied from the 
equator to the poles, 30 inches of mercury in the barometer 
indicated a less gaseous pressure, and consequently less density 
of the atmosphere, at the equator than 30 inches at the poles, 
and hence a correction for latitude should be introduced in 
allowing for refraction. He showed that, for the difference of 
latitude of Pulkowa and Washington, it would make o”1 differ- 
ence in the refraction at 45° of zenith-distance, and might be 
sufficient partly to account for differences in systems of star 
declinations which depended upon observations at great zenith- 
distances. 
In the Section of Biology, the paper of Messrs. J. M. Coulter 
and J. N. Rose, giving a synopsis of the North American pines, 
based on leaf-structure, was of especial value from a systematic _ 
stand-point, from the fact that any species in this somewhat 
difficult group can at once be distinguished by the peculiarities 
of its minute leaf-structure ; and the results of the author’s ob- 
servations are shown to be worthy of attention from the fact that 
a classification based on these characters is, in its broader features, 
closely like that of the late Dr. Engelmann, which, as is well 
known, took into consideration the whole tree. 
The relations of germs to disease naturally occupied a pro- 
minent place in the proceedings of the Section, and the presence 
of over half a dozen investigators in this line made the discussions 
interesting. Dr, D. E. Salmon read two papers bearing on the 
causes of immunity from a second attack of germ diseases. 
There are three possible explanations :—(1) Something is de- 
posited in the body during the attack which is unfavourable to 
the germ ; (2) something has been withdrawn which is necessary 
to its development ; (3) the tissues have acquired such a toler- 
ance for the germ or for an accompanying poison that they are 
no longer affected by it. Dr. Salmon favoured the last view, 
and gave details of a large number of experiments to substantiate 
his opinion. He said that Metchinkoff’s phagocyte theory was 
not wholly satisfactory, and that large doses of the germs were 
more powerful than small ones. He attributed their action to a 
poison which was a result of their growth, and thought that a 
large dose had a greater effect because the poison benumbed or 
killed the cells, thus giving the Bacteria a better chance to grow 
and to thus produce more poison. 
Dr. Joseph Jastrow gave an account of some physiological 
observations on ants, in which he was able, by simple but inge- 
nious means, to study the rate of walk of these insects, and 
stated that his results, so far as they went, confirmed the opinions 
of others that the smaller the animal the more rapid the step, 
and also the more quickly fatigue was produced. Dr. Jastrow 
also had some observations on the dreams of the blind, taken 
mostly from persons who had lost the sense of sight before the 
age of five. In these cases the dreams were all in terms of 
hearing. In the case of Laura Bridgeman the dreams were ap- 
parently based on touch. In persons who become blind between 
five and seven, sight terms played an important part in dreams. 
The relation of these facts to the development of the sight- 
centres was pointed out, 
PHOTOGRAPHIC DETERMINATIONS OF 
STELLAR POSITIONS 1 
[It has been suggested that a short account of my work upon 
stellar photographs for the attainment of accurate obserya- 
tions might be acceptable to the astronomical section. My in- 
tention had been to attend this meeting as a listener and learner 
only, but I comply with the suggestion the more readily, since, 
by a notable coincidence, I spoke upon the same subject in this 
place just twenty years ago this week. It is true that my com- 
munication then was only an oral one, and never reduced to 
writing, for the successful establishment of the Atlantic cable, 
of which I had received notice that day, called me away sud- 
denly, before the time fixed for the regular presentation ; but an 
elaborate written memoir upon the subject had been presented 
to the National Academy, ten days previous, at Northampton. 
The early history of celestial photography is demonstrably 
and exclusively American ; and its use as a method of delicate 
quantitative research is very markedly so. Without entering upon 
t Paper read at the Buffalo Meeting of the American Association for the 
Advancement of Science, August 20, 1886. 
es 
ee 
trea ai glen eee ent Ne NAEP LLL AGG ALENT i CLT A COA A Sree 
