22 NATURE 
x 
[SEPTEMBER 7, 1916 
three or four periods, but the three elements are not 
always simultaneously affected, and no periodicity for 
the abnormal maxima can yet be established. 
A Faint Star witH LarcGE Proper Mortion.—The 
greatest proper motion yet known for any star has 
been discovered by Prof. Barnard from a comparison 
of photographs taken with the 1o-in. Bruce telescope, 
with the aid of .the Zeiss blink-microscope. The star 
in question is one of the 11th magnitude, situated in 
R.A. 17h. 53m. 44s., declination +4° 27-4’ (1916-0), 
and the annual proper motion, in a northerly direc- 
tion, amounts to about 10”. The star follows 
B.D.+4° 3560 by g:5s., and is 0-4! north. The motion 
is confirmed by numerous plates taken at Harvard, 
dating from 1888 (Harvard Bulletin, 613). The 
greatest proper motion previously known was that of 
Cordoba zones, sh. 243, magnitude 8-3, R.A. 5h. 8m., 
declination —45°, amounting to 8-7" per annum. The 
well-known star, 1830 Groombridge, of magnitude 
65, comes next with a proper motion of 7” per 
annum, ; 
Tue Van ViEcK OsseRvaTory.—The Van Vleck 
Observatory of Wesleyan University at Middletown, 
Connecticut, was dedicated on June 16. The observa- 
tory is the gift of the late Joseph Van Vleck, in com- 
memoration of the services rendered to the University 
by his late brother, John Monroe Van Vleck, who 
had been professor of mathematics and astronomy for 
many years. The chief instrument is an equatorial 
refracting telescope of 18}-in. aperture and, 26 ft. focal 
length, but the completion of the objective has been 
delayed by the war, and a 12-in. lens is temporarily in 
use. The observatory is designed for purposes of in- 
struction and research, and, in addition to the large 
telescope, is provided with two small transits and 
_ Numerous portable instruments. The director is Prof. 
F. Slocum, who is well known for his successful work 
at the Yerkes Observatory. It is intended to apply 
the large telescope chiefly to the photographic deter- 
mination of stellar parallaxes (Popular Astronomy, 
vol. xxiv., No. 7). 
THE SysTEM OF Potaris.—Spectroscopic observations 
have revealed the existence of two close companions 
to Polaris, one having a period of about four days, and 
the other of about twelve years. From a discussion 
of all the available data, L. Courvisier, of the Berlin- 
Babelsberg Observatory, has concluded that the visible 
gth magnitude companion to Polaris is also a member 
of the system, its period of revolution being at least 
20,000 years (Astronomische Nachrichten, 4854). The 
mass of Polaris itself is probably not greater than 
one-fourth that of the sun, and its density not more 
than 0-003 of the sun’s density. The deduced parallax 
of Polaris is 0-053". The maximum separation of the 
companion having a period of twelve years is given 
as 0-20", and this may be reached about the beginning 
of next year. 
THE AMSTERDAM COLONIAL INSTITUTE. 
For some years past a movement has been in pro- 
gress in Holland having for its object the founda- 
tion of a colonial institute in Amsterdam commensurate 
with Dutch colonial interests, and adequately repre- 
sentative of the important part which Holland has 
taken in the prosecution of research in tropical agri- 
culture and forestry. There has existed at Haarlem for 
many years a small, but important, colonial museum, 
"and the promoters of the new institute have fortunately 
been able to secure the transfer of the economic 
collections, publications, and staff of the Haarlem 
museum to the Amsterdam institute. The latter is at 
present housed in temporary quarters, but the authori- 
NO. 2445, VOL. 98] 
ties have in hand a capital sum of about 1,600,000 
florins, which is apparently all available for the con- 
struction of buildings and the installation of the new 
institute. The latter will apparently be supported 
mainly by subsidies from the Government, the province’ 
of North Holland, and the city of Amsterdam, and by 
subscriptions from private individifals and firms. In 
1g1q the ordinary annual expenditure was 91,600 
florins, but for 1915 the estimate is 78,000 florins, 
certain of the subsidies having been cut down owing 
to war economies. ? Me. 
As at- present organised, the institute comprises” 
three sections: Economic (which: is practically the 
Haarlem museum transferred to mew quarters), 
Anthropological, and Tropical Hygiene. It corre~ 
sponds, therefore, on a small scale to the Imperial 
Institute of the’ United Kingdom as regards technical 
and economic work on colonial products, and to the 
British Schools of Tropical Medicine as regards 
tropical hygiene. There is, of course, nothing in this 
country as yet corresponding to the anthropological 
section of the Amsterdam institute. A site for the 
new buildings has been secured on the Oosterbegraaf- 
plaats, where a building to house the administrative 
offices and the economic and anthropological sections 
will be erected with a front of about 170 yds. on the 
Maurits Kade and about 75 yds. on Linnaeus Straat. 
A special building for the section of tropical hygiene 
will be erected as part of the buildings of the Hygienic 
Institute of the University of Amsterdam, with which 
this section will work in close co-operation. 
The institute has already issued a number of publi- 
cations, perhaps the most interesting being a concise 
history by Dr. Sirks of research in natural science in 
the Dutch East Indies (Koloniaal Instituut te Amster-. 
dam, Mededeeling, No. vi. 
museum, No. 2). 
COMMITTEE of the U.S. National Academy of 
Sciences spent the last fortnight of the year 
1915 On the Canal zone studying the great land- 
slides of the Culebra Cut. These are three in num- 
ber, and are all comprised within a mile or a little 
more of the Canal bank. The moving ground con- 
sists almost entirely of the stratified rocks known as 
the Cucuracha or Culebra beds. The East Culebra 
slide and the Cucuracha slide lie north and south of 
the core of basalt and hard tuff which forms the high 
central mass of Gold Hill, the flanks of which are 
composed of the aforesaid stratified rocks. On the 
west side of the Canal there are three summits of 
massive rock, tuff or basalt, viz. Contractor’s Hill, 
nearly opposite to Gold Hill; Zion Hill, north of Con- 
tractor’s Hill; and Culebra Hill, north of Zion Hill. 
The third great slide, the only one on the west bank 
of the Canal, known as the West Culebra slide, lies 
between Zion and Culebra Hills. 
The committee finds that no great extension of the 
slides in the soft Cucuracha or Culebra beds is prob- 
able, because the rock itself is limited in extent, and 
because the broken ground already extends in many 
places beyond the crest of the slope. 
It also reports upon the important question of the 
stabilitv of Gold Hill. Contractor’s Hill, Zion Hill, 
and Culebra Hill, which rise considerably above the 
level of the sliding ground. The confident expectation 
that these eminences will “slide”? makes the average 
visitor to the Canal works pessimistic of the future 
of the undertaking. Viewed casually, or from a dis- 
1 Preliminary Report upon the Possibility of Controlling the Land Slides 
Adjacent to the Panama Canal. By the Committee of the National Academy 
of Sciences aprointed at the reauest of the President of the United States: 
(Proc. Nat. Acad. Sci., vol. ii., No. 5, April 15, 1916.) 
Afdeeling Handels- 
