359 

spread over an area of several kilometres! There is 
little difficulty in constructing a bomb which shall 
explode at a given distance above the ground and 
produce a dense cloud, but it is doubtful whether sucha 
smoke cloud could be made to spread over anything 
like a distance of kilometres. We are told further 
that these bombs will prevent attack by anti-aircraft 
guns and aeroplanes. How it is to stop the latter, 
which travel at a much higher speed than a dirigible, 
and will certainly attack from above or at least on a 
level with the Zeppelin, is not clear. In the absence 
of any dissipating wind a Zeppelin free to choose 
her course may derive considerable advantage from a 
smoke bomb burst over a gun position, but some shots 
should certainly be fired before she has time to locate 
the gun, and then she must get well over the position 
to place the bomb effectively. Smoke is a very vague 
term, and whilst it may obscure physical vision may 
also be used to cover something far more dangerous. 
In this connection the warning issued by the Com- 
missioner of Police to keep all windows and doors 
on the lower floors of houses closed, in the event of an 
air-raid, to prevent the access of deleterious gases is 
not without significance, and should certainly not pass 
unheeded. 
Tue service of radio time signals which is now 
provided by the Union Government wireless telegraph 
stations at Cape Town (Slangkop) and Durban will 
be of inestimable value to shipping in South African 
‘waters. By means of such a service, vessels within 
range of the stations. can ensure a_ precision . of 
standard time which it would otherwise be impossible 
for them to obtain, and the new facilities should 
make for added safety in navigation. The Cape Town 
(call letters VNC) and Durban (VND) stations are 
open night and day, and work on a 600-metre normal 
wave. 
is adapted to give automatically a series of signals 
extending over an interval of half a minute. The 
signals are transmitted at 11 p.m, Union time, which 
is equivalent to 9 p.m. Greenwich mean time, and 
shortly before that hour the clock is brought into 
conformity daily with the observatory standards. The 
time signal proper, which is preceded by ‘the usual 
warning signal, consists of twelve dashes, each of 
about three-quarters of a ‘second in duration, divided 
into five groups, the commencement of the separate 
dashes corresponding exactly with the following 
Greenwich mean times :— 
Group I. Group II. Group III, Group IV. Group V. 
Is ire eee Nh fis) Sp h. m. 5s. h. ms. ne Soe 4 
eee De Q ore On yn ae 
8°59 30. 8 59 38. 8 59 44 8 59 48 «8 59 54 
3°59 32 8 59 40 8-59 50 8 59 56 
8 59 34 8 59 58 
ito) 
° 
° 
[o) 
° 
By means of a special relay the time signal is simul- 
taneously transmitted to the Cape Town and Durban 
wireless stations, the signa! to the latter station pass- 
ing over the land telegraph wire connecting Cape 
Town and Durban, a distance of about 1100 miles. 
In addition to the time signals, both stations transmit 
each day, at 1 p.m., a report in plain language con- 
ee information concerning the meteorological 
0, 2378, VoL. 95] 
NATURE 
A special clock at the Cape Town Observatory, 

[May 27, 1915 

conditions prevailing on the whole coast of: the Union 
of South Africa. ; 
Tue Popular Science Monthly for April contains a 
series of fifteen short articles dealing with American 
economic and social problems arising out of the war. 
Stress is laid primarily upon the necessity for the 
education of the American people in methods of main- 
taining health and prolonging life; it is shown that 
“degenerative diseases’? are causing an increased 
death-rate which was nearly doubled between 1880 
and 1g10. .The average man is not an able-bodied 
citizen; he is far below the attainable standard of 
physical soundness and efficiency.- The war appears 
to cause the American to loolk more closely upon the 
value of a hunan life. ‘A second point arises out of 
a consideration of the American mercantile marine. 
The merchant navy of the United States is totally 
inadequate to the carrying of more than one-tenth of 
the American trade. Americans are advised to seek 
for foreign trade with the same energy as they display 
in capturing markets in distant parts of the United 
States, and the Englishman is amused to learn that 
the American exporter is suspected of bad packing, 
lack of adaptability, and the dozen or so other faults 
which are alleged to be manifest among English ex- 
porters. Taken as a whole, the series is symptomatic 
of the stimulus which results from war; nothing can 
be quite the same again; distant America will share 
with the rest of the world in the changes, and notable 
Americans here display the tendency of their thoughts. 
The occasion for these articles was the meeting of the 
American Association for the Advancement of Science 
in December last. 
Tue Zoological Society of Philadelphia is to be 
congratulated, since, according to its forty-third 
annual report, among a consignment of young bears, 
shipped from Europe as “‘ Russian bears,’’ two, a male 
and a female, prove on examination to be specimens 
of the rare blue bear of Tibet (Ursus pruinosus). The 
pathologist’s report contains some valuable data on 
tuberculin tests, carried out on monkeys and birds, 
on enteritis among quails, and on larval and adult 
hook-worms, which were the cause of considerable 
mortality among the Canidz during the year. Per- 
haps the most important parisitological item of the 
year was the discovery of cysts of Coccidium bige- 
minum in the faeces of a fox. This parasite has been 
found three times in man, and frequently in dogs, 
but it has never before been found in a wild animal. 
Many items of more than usual interest are to be 
found in the Report of the South African Museum for 
IQI4. In the first place, the director, Dr. Louis 
Péringuey, is able to state that the agitation, started 
some time ago in the Uitenhage district, for the 
destruction of the elephants in the Addo Bush, has not 
only failed, but that the Provincial Government is 
taking steps to ensure the safety of the three troops 
known to occupy the preserve. The herd apparently 
will have to be thinned, but no indiscriminate shoot- 
ing will be allowed, and provision will be made for 
ensuring to the remainder a fair supply of water, the 
lack of which is oftener than not the cause of the 




