s30) 
INATIOLEE, 
[ FEBRUARY 4, 1904 
velopment of scientific knowledge from the time of Thales 
to the present epoch; and though it is impossible to com- 
press the history of science into 450 pages, the author’s 
survey of progress is excellently conceived and carried out. 
Original texts and illustrations are given prominence, so 
that the student who reads the work cannot fail to 
derive inspiration from it. For students interested in 
special branches of exact science Ostwald’s ‘* Klassiker 
der exakten Wissenschaften ’’ are available, and for those 
who require a general view of scientific progress, constructed 
in the same spirit, Dr. Dannemann’s volume is excellently 
adapted. 
WE have received vol. xxii. of the Geographical Journal, 
which contains the monthly parts from July to December, 
1903. As usual, the volume is remarkable for the large 
number of its excellent illustrations and for the plentiful 
Among 
many other valuable contributions the following may be 
mentioned :—the account of the first year’s work of the 
National Antarctic Expedition, by Sir Clements Markham, 
K.C.B., F.R.S.; the bathymetrical survey of the fresh-water 
lochs of Scotland, under the direction of Sir John Murray, 
K.C.B., F.R.S., and Mr. L. Pullar ; a scheme of geography, 
by Prof. W. M. Davis; terrestrial magnetism in its relation 
to geography, by Captain E. W. Creak, F.R.S.; four years’ 
Arctic exploration, 1898-1902, by Commander R. E. Peary; 
and the Alaska boundary, by Colonel Sir T. H. Holdich, 
ReGen Gena e Geb. 
supply and high character of the coloured maps. 
Tue additions to the Zoological Society's Gardens during 
the past week include a Vervet Monkey (Cercopithecus 
lalandii) from South Africa, presented by Mr. J. Fisher; 
a Green Monkey (Cercopithecus callitrichus) from West 
Africa, presented by Mr. H. R. Broad; a Japanese Deer 
(Cervus sila) Japan, presented by Mr. Leopold 
de Rothschild; a Common Squirrel (Sciurus vulgaris), 
British, presented by Captain Locock; an Allied Hornbill 
(Penelopides affinis) from the Philippine Islands, presented 
by Mrs. Johnstone; a Rough-legged Buzzard (Archibuteo 
lagopus), European, presented by Mr. E. A. Maling; two 
Blue and Yellow Macaws (Ara ararauna) from South 
America, presented by Mr. Charles Storey; two Kestrels 
(Tinnunculus alaudarius), British, presented by Mr. A. H. 
Bishop; a Hainan Gibbon (Hylobates hainanus) from the 
Island of Hainan, a Variegated Spider Monkey (Ateles 
variegatus) from the Upper Amazons, a Crowned Hawk 
Eagle (Spizaetus coronatus) from Africa, a Blue-rumped 
Parrakeet (Psephotus haematonotus) from Australia, de- 
posited; a Campbell’s Monkey (Cercopithecus campbellt) 
from West Africa, purchased. 
from 
OUR ASTRONOMICAL COLUMN. 
Pecutiar Forms or Comers’ Tarts.—At a meeting of 
the National Academy (U.S.A.) held at Chicago on 
November 18, 1903, Prof. E. E. Barnard read a paper deal- 
ing with the anomalous appearances sometimes observed 
oa photographs of the tails of comets. Accepting the 
generally adopted theory that the tails are caused by the 
repelling action of the sun’s light on the cometary particles, 
he demonstrated that the broken appearance often observed 
in the tails may be due to the external influence of some 
resisting medium, possibly groups of meteorites which are 
in all probability scattered throughout space. Thus the 
sudden contortions of the tail of Brooks’s comet on and after 
October 22, 1893, might be explained by the supposition 
that it encountered a swarm of meteorites which caused the 
extraordinary detachment of the cloud-like masses seen on 
the photographs obtained between October 22 and November 
3 might have been produced 
3. A similar .phenomenon 
NO. 1788, VOL. 69] 
had the detached portion of the tail of Borrelly’s comet 
(1903), after its separation from the nucleus, encountered 
any similar resisting medium. Prof. Barnard directs atten- 
tion to the fact that in the latter case the detached portion 
gave no evidence of accelerated motion of repulsion such 
as would be expected if the repulsion were solely due to the 
action of the sun’s light. 
Several beautiful photographic reproductions of the 
various comets discussed by Prof. Barnard accompany his. 
paper in the January number of Popular Astronomy. 
Actinic QuaLity oF Sky-LiGHT.—Mr. Gavin J. Burns has 
recently published the results of some experiments made by 
him in order to determine the relative actinic qualities— 
not intensities—of the light received from the star-lit sky 
near the zenith on a clear night, of moonlight, of sunlight, 
and of the light received from the zenith during the day- 
time. 
With ordinary, bright light-sources the usual method of 
procedure in determining the ratio of actinic to non-actinic 
rays (i.e. the actinic quality) in the total radiation is to 
analyse the latter, in detail, spectroscopically, but in the 
experiments performed by Mr. Burns the total radiations 
were far too faint for the application of this method. He 
therefore divided the spectrum generally into two parts, 
actinic and non-actinic, and in order to obtain com- 
parative results used layers of two liquids as screens, 
the first a solution of bichromate of potash, which totally 
absorbed the blue, violet, and ultra-violet rays, the 
second a_ solution of methyl-violet, which absorbed 
the orange, yellow and green. In each experiment a 
layer of known absorptive effect was placed between the 
photographic plate (Edwards’s isochromatic) and the light 
source. The plate was then exposed to the light for a 
known period and developed, and then the various results 
were reduced to standard conditions and compared. From 
the results thus obtained Mr. Burns concludes that the 
actinic quality of the light which reaches us from the zenith 
sky by night, when the sun is at least 18° below the horizon, 
is greater than that of moonlight from the moon on the 
meridian, or sunlight when the sun has an altitude not 
greater than 36°. It is also greater than the average value 
for the light of the blue, cloudless sky by day. On the 
other hand, the observations give no information as to the 
real relative actinic qualities of sunlight and sky-light, for 
observations of both sources at equal altitudes must be made 
to determine this ratio (British Astronomical Association 
Journal, vol. xiv., No. 2). 
Tue Unitep States NavaL Osservatory.—The report of 
the United States Naval Observatory for the year ending 
June 30, 1903, contains a general review, by the director, 
Captain C. M. Chester, U.S. Navy, of the personnel, the 
work and the results obtained during that period. 
Among a number of recommendations as to the future 
work, the director suggests that subsidiary observatories 
should be founded on several of the islands governed by the 
United States in the Pacific. Tutuila, Samoa, situated in 
lat. 15° S., is especially mentioned in this respect as being 
generally recognised as an ideal site for an astronomical 
observatory, and it is suggested that 500 of the 1597 stars 
adopted at the International Conference of Naval Observ- 
atory Directors in 1896 should be observed there by an 
assistant from Washington, who, with the assistance of the 
naval officers and men already stationed there, could also 
make observations of the magnetic elements obtaining on 
the island. 
The director also recommends that one of the ships 
attached to the European Squadron of the U.S.A. Navy 
should be deputed to assist a small party of astronomers 
from Washington in observing the total eclipse of the sun 
in Spain in 1905. In support of this recommendation he 
quotes from the report of Sir Norman Lockyer, on the Indian 
eclipse of 1898, as to the valuable assistance rendered by the 
officers and men of H.M.S. Melpomene, at the suggestion 
and under the direction of that observer, in making observ- 
ations of various eclipse phenomena. 
Each of the sectional reports has been written by the 
officer in charge of the particular section reported on, but 
the results obtained are far too numerous to be given in 
detail here. 
The time service, which operates 18 official time balls and 
