DECEMBER 24, 1903] 
dential address for 1902, by Captain F. W. Hutton, F.R.S., 
dealt with evolution and its teaching. We have also re- 
ceived a copy of the Walker memorial volume published 
by the Royal Society of Tasmania, and containing the 
papers on early Tasmania read before the Society during 
the years 1888-1899 by the late Mr. J. B. Walker, vice- 
chancellor of the Tasmanian University. 
Tue report of the U.S. National Museum for the year 
ending June 30, rg01, has just reached us from the Smith- 
sonian Institution. Part i. of the volume (of 452 pages) 
contains the report of the assistant secretary and the reports 
of three head curators, a list of accessions to the museum, 
and a bibliography of the publications of the museum. The 
second part will, however, prove of more general interest, 
consisting as it does of five lavishly illustrated articles. 
These contributions are, first, a report describing the ex- 
hibit of the U.S. National Museum at the Pan-American 
Exposition at Buffalo in 1901, by Messrs. F. W. True, 
W. H. Holmes, and G. P. Merrill. This report is iJlus- 
trated by seventy-two full-page plates, which it would be 
difficult to improve. Mr. W. H. Holmes also describes the 
flint implements and fossil remains from a sulphur spring 
at Afton, Indian Territory, this article being accompanied 
by twenty-six plates; and the same author deals with the 
classification and arrangement of the exhibits of an anthro- 
pological museum. Mr. Walter Hough discusses archzo- 
logical field work in N.E. Arizona, and gives an account 
of the Museum-Gates Expedition in 1901, and with this 
monograph there are 1o1 plates, some of which are beauti- 
fully coloured. The last contribution is by Mr. J. B. Steere, 
and is a narrative of a visit to Indian tribes of the Purus 
river, Brazil. 
A QUANTITATIVE study by Dr. Paul von Schroeder 
(described in the Zeitschrift fiir physikalische Chemie) of the 
setting and swelling of gelatin has led to some interest- 
ing observations, which not only throw light on the pheno- 
mena of gelatinisation, but also form an important addition 
to our knowledge of reversible chemical changes. It 
appears that gelatin solutions undergo two types of change, 
a non-reversible hydrolysis by which the setting power of 
the solution is permanently impaired, and a _ reversible 
change as the result of which the jelly melts when heated 
and slowly solidifies when cooled. The setting power of a 
solution is accurately indicated by its viscosity. If after 
rapidly cooling from 100° the viscosity is measured at 25°, a 
low value is obtained which gradually increases until, if 
the decomposition of the gelatin has not proceeded too far, 
it culminates in the setting of the whole mass. By 
measuring the increment of viscosity during one hour it 
is possible to predict whether the solution will set in the 
course of the next twenty-four hours. The reverse process 
by which the gelatin swells and then dissolves in water 
presents similar points of interest. Gelatin saturated with 
water has a higher vapour-pressure than water itself, and 
loses weight in a saturated atmosphere; the difference of 
vapour-pressure is, however, very minute, and may be com- 
pared with that which exists between drops of different 
Sizes, and causes the larger drops of a fog to grow at the 
expense of the smaller particles. 
AT a meeting of the Institution of Civil Engineers on 
December 15 several aspects of the important question of 
water supply were discussed. Prof. J. Campbell Brown 
read a paper on deposits in pipes and other channels con- 
veying potable water. Analyses were given of incrust- 
ations on iron pipes, showing that these incrustations were 
due to oxidation of the iron of the pipes, whether wide- 
NO. 1782, VOL. 69] 
NATURE 
185 
spread or in nodules, and that they were not limited to 
acid waters, but were common to acid, alkaline, and neutral 
waters. Investigations were recorded showing that slimy 
deposits on the inner surface of pipes, &c., were produced 
by gelatinous and filamentous iron-organisms which grew 
and extracted iron from the water, and died at one end 
while they grew at the other. Solid rock particles were 
entangled in this slime, and binoxide of manganese was de- 
posited by chemical action, and this also was entangled in 
the mass of the gelatinous iron-organisms. Messrs. Osbert 
Chadwick and Bertram Blount introduced the subject of 
the purification of water highly charged with vegetable 
matter, with special reference to the effect of aération. 
They showed that the purification of tropical waters was 
very difficult; they had found that treatment with iron was 
efficacious, but the treatment must be more thorough than 
with ordinary water-supplies. The character of these 
waters charged with vegetable matters rendered the removal 
of the iron difficult. Systematic aération, so as to ensure 
an abundant supply of oxygen, was requisite. An apparatus 
had been devised in which the water was caused to flow 
through perforated plates, emerging in streams of small 
diameter and exposing so large a surface per unit volume 
of liquid that rapid absorption of oxygen from the air was 
made certain. 
Tue additions to the Zoological Society’s Gardens during 
the past week include two Malabar Mynahs (Poliopsar 
malabaricus) from India, presented by Mr. AWE er Wines, 
two South Albemarle Tortoises (Testudo vicina) from the 
Albemarle Islands, presented by the Captain and Officers 
of H.M.S. Amphion; two Hybrid Parrakeets (between 
Palaeornis eximius and Psephotus haematonotus), four 
Limbless Lizards (Pygopus lepidopus) from Australia, de- 
posited. 
OUR ASTRONOMICAL COLUMN. 
RapiAL VELOCITIES OF B Auric®.—M. G. A. Tikhoff, of 
the Pulkowa Observatory, has recently concluded a research 
on the relative velocities of the spectroscopic binary 
B Auriga, and publishes his results in No. 3916 of the 
Astronomische Nachrichten. 
The forty-one plates on which the results are based were 
obtained by M. Belopolsky, nineteen during the early part 
of 1902 with a Rutherford spectroscope, and twenty-two 
at the end of 1902 and the beginning of 1903 with a 
new Topfer three-prism spectrograph. The relative veloci- 
ties of the components are given in a table, which also 
shows the exact time at which the plates were taken and 
the interval since the last conjunction, and they show a 
maximum of 228 km. per second, on March 24, 1902, to 
zero. 
The curve obtained on plotting these results gave 
3d. 23h. 30-4m. as the period, and it also indicates that the 
system is not only a binary one, as announced by Prof. 
Pickering in 1890, but is made up of more than two bodies. 
This is confirmed by the spectrogram obtained on January 
21, 1903, in which the line Hy is made up of four com- 
ponents, indicating the existence of four separate bodies 
with different velocities. 
M. Tikhoff has arrived at the conclusion that the system 
is made up of two pairs, each pair consisting of a star 
giving strong lines and another giving weak lines, and each 
element making a complete revolution about the centre of 
gravity of its pair in 19-1 hours. The ratio of the masses 
of the two groups is near unity, and the proper motion of 
the whole system as deduced from the magnesium lines at 
A 4481 and A 4352 is —16 km. per second. The epoch of 
conjunction may be taken as February, 1903, 3d. oh. 
(Pulkowa M.T.). 
Tur “ DoustinG ”? oF THE Martian Canats.—In discuss- 
ing the instrumentality of ‘‘ contrast’ in producing the 
duplicated appearance of Martian canals, M..-E:. M. 
