74 
NWATURE 
[Marcu 18, 1915 

comparison with that. of the more erect modern Aus- 
tralian. The Piltdown type is regarded as even older 
than that represented by the mandible found at 
Mauer, near Heidelberg, in 1907. In stating that the 
immediate predecessor of modern man in Europe was 
of Neandertal type, Dr. Smith Woodward does not 
exclude the possibility of the contemporaneous exist- 
ence of a type with less retreating forehead. The 
Transactions of the Perthshire Society of Natural 
Science (vol. vi., 1914) contain a paper by Dr. Lyell, 
in which the existence of man throughout the Glacial 
epoch is emphasised; and Mr. R. A. Smith’s paper 
on prehistoric problems in geology, with the well- 
reported discussion on it (Proc. Geol, Assoc., vol. 
XXvVi., 1915, p. 1) shows how far we have got from 
the old prejudices, which would have us believe that 
a deposit containing flint implements must necessarily 
be of post-Glacial age. 
Tue nature of ‘‘nardoo,’’ the supposed nutritive 
food which led to such disastrous-results during the 
ill-fated expedition of Burke and Wills, is discussed 
, by Mr. E. H. Lees in the January issue of the 
Victorian Naturalist. It has been assumed that the 
true nardoo is made from the spores of a species of 
Marsilea growing in the swamps of Victoria. This, 
however, appears to be quite innutritious by itself, 
and nardoo made from leguminous seeds of various 
Ixinds is stated by the author to have been formerly 
supplied in establishments kept by natives. He main- 
tains, in fact, that, in place of being the product of 
any oné particular plant, nardoo is a compound made 
from several. 
AN investigation into the limits within which the 
combined hysteresis and eddy current losses in iron 
per unit mass can be expressed by a single expression 
of the form, W=cB”, has been carried out at Liver- 
pool by Mr. N. W. McLachlan, who describes his 
results in a contribution to the Journal of the Insti- 
tution. of Electrical Engineers. Measurements were 
made by the Epstein alternating-current method with 
various brands of iron, and the curves obtained were 
analysed. It was finally found that such a formula 
would be accurate within from 1-5 to 2-5 per cent, 
for various materials tested, between the flux densities 
of 4000 or 5000 and 10,000 lines per sq. cm., and 
frequencies from 26 to 60 cycles per sec., the index 
n varying from 1-68 to 1-83, according to the material. 
Going closer into the matter, the constant c was 
found to vary directly with the frequency and the 
relation which exists between n and f was of the 
form n=cf". 
Tue results of a long series of researches'on the 
conditions affecting the strength of wireless signals is 
published in a paper by Prof. E. W, Marchant, read 
before the Institution of Electrical Engineers recently. 
Daily observations, unhappily interrupted by the war, 
were made at Liverpool of the strength of signals 
sent out by the Eiffel Tower with a carefully calibrated 
apparatus and recorded by a suitable galvanometer. 
Attempts were made to draw general conclusions from 
the result, but in the opinion of several well-known 
wireless telegraph engineers who took part in the 
NO. 2368, VOL. 95| 


‘discussion, there was, in the absence of a control 
station near Paris, scarcely sufficient proof that the 
variations in received signal strength were due entirely 
to the degree of ionisation or other conditions in the 
intervening medium. Be this as it may, however, 
Prof. Marchant was able to show that the ratio 
between the day and night signal strength varies with 
the time of the year, and that the strengthening after 
sunset is less marked in rain than in clear weather, 
and is different in different directions. The greatest 
variations were observed at night. In his own opinion, 
moreover, the character and strength of the variations 
do point to the conclusion that the main factor which 
controls them is the state of ionisation of the atmo- 
sphere; he suggests that clouds of ionised air may 
exist in the upper regions of the atmosphere which act 
as mirrors for the waves and cause the sudden changes 
in signal strength that have been observed. 
THE applications of electrical engineering to war- 
fare formed the subject of an exceptionally interesting 
discussion at the Students’ Section of the Institution of 
Electrical Engineers on March 3, under the chairman- 
ship of Mr. W. Duddell. Mr. P. R. Coursey opened 
the discussion on ‘‘Communications,” stating that the 
utilisation of the electrical telegraph for military pur- 
poses dated back only to the Boer war. In the Russo- 
Japanese war, field telegraphy and telephony, and also 
wireless telegraphy, were used; while in the present 
war not only do field telephones, and telegraphy with 
Morse sounders-and ‘‘vibrator”’ instruments take an 
important part, but telegraphy is so much employed 
that transmission with Wheatstone automatic instru- 
ments actually finds useful application. Use is also 
made of wireless telegraphy. In the course of the 
discussion it was mentioned that, for wireless telegraph 
reception by airmen, pneumatic head-piece ‘* shocls- 
absorbers”’ are employed to deaden the noise of the 
engine. The subject of ‘‘The firing of mines and 
explosives ’’ was opened by Mr. S. Killingback, who 
said that electric firing had the advantage over hand 
firing with time fuses, that it was more convenient 
and trustworthy, and also rendered possible remote 
control and the simultaneous firing of several charges. 
The standard electric fuses and detonators require 
about o:8 ampere to actuate them, and are fixed either 
by accumulators or portable hand-operated service 
dynamos. - One speaker in the discussion expressed 
the opinion that trinitrotoluene was superseding gun- 
cotton and gunpowder for the fuses, and another 
stated that electric firing had not been employed in the 
Russo-Japanese war, suggesting that its chief field in 
warfare was for the firing of mines for harbour pro- 
tection for which more trustworthy and permanent 
cables could be laid. Mr. Duddell reminded the meet- 
ing of an exploder (of German make) captured from 
the Boers, which had been preserved in the Institution 
library. 
Tue harmful effects of aldehydes in soils are de- 
scribed by O. Schreiner and J. J. Skinner in Bulletin 
No. 108, Bureau of Soils, U.S. Department of Agri- 
culture. In the course of examination of an acid 
garden soil for organic substances, salicylic aldehyde 
| was isolated in amount sufficient to enable its effects 
