660 
production and life of the Main Reef Series, Witwatersrand, 
down to 6000 feet, and then deduce what, in the circumstances, 
they consider to be a fair estimate. They conclude that it must 
be assumed that the annual production will -increase for a few 
years to a maximum, will be maintained for a second period, 
and that then there will be a third period of decline. For the 
three years preceding the war, the average increase of production 
was at the rate of 4,000,000/. per annum, the production for 
1899 having a value of about 19,000,000/, Allowing eighteen 
months from January 1, 1902, for the industry to be restored to 
the conditions existing in August, 1899, a similar increase of 
production will bring the output to at least 30,000,000/. per 
annum by June 30, 1906, and if this rate of production were to 
be maintained from then on, the total production of 
1,233,560, 709/. would give a life from January 1, 1902, of 424 
years. But as the production will decline gradually instead of 
coming to a sudden stop, this length of life will be increased, 
unless the annual output should for any considerable period 
exceed 30,000,000/., when the increase in length of life due to 
declining output would be neutralisec, 
.Mr. C. J. Woopwarp, Municipal Technical School, Bir- 
mingham, sends us a photograph, from which the accompanying 
illustration has been reproduced, showing Indians in the art of 
producing fire by means of the fire drill. The photograph is a 
copy of one in the possession of Mr. Henri d’Este, and was 
taken in the Orinoco region of South America. 
IN a recent number of the S7/zwngsherichte of the Vienna 
Academy of Sciences, Dr. J. Hann contributes an important 
paper on the meteorology of the equator, based on observations 
taken by Dr. E. Goeldi, director of the museum at Para. Very 
few stations exist near the equator, and especially equatorial 
South America ; the observations now in question extend from 
August, 1895, to August, 1901, and, although’ they are still 
continued, Dr. Hann considers them to be of such exceptional 
value that he has preferred to submit them to an elaborate 
discussion rather than to wait for later materials. In this note 
we shall refer only to temperature and rainfall. © The results 
show that the temperature is extremely uniform throughout the 
year ; the annual variation amounts only to 1°°4 C., while the 
mean daily variation is $°°8. The lowest temperature occurs in 
the beginning of the year, and the highest at the end of the year ; 
from May to September the mean temperature is almost constant. 
The yearly mean is 25°°7 C. The rainfall is characterised by a 
NO. 1722, VOL. 66] 
NATURE 
' which the country has undergone. 
[OcTOBER 30, 1902 
wet season, January to April, and a relatively dry period, from 
May to December, although rain is somewhat frequent during 
the dry season. The falls occur almost exclusively in the 
afternoon and evening, during thunderstorm weather. The 
mean annual rainfall is about 102 inches. 
A survey of the principal changes that have occurred in the 
birth and death rates in Italy during the last forty years has been 
given by Prof. Giuseppe Sormani in the Lombardy Rendiconti, 
xxxv. 16, The principal conclusions are as follows :—The birth 
rate fluctuated between the limits 39°34 per 1000 in 1876 and 
33°49 in 1898, while the corresponding limits of the death rate 
were 34°39 in 1867 and 21°87 in 1899. The fluctuations are thus 
seen to be less marked in the birth rate than inthe death rate, 
but both show a downward tendency, which occurs to a great 
extent concurrently with the introduction of improved sanitary 
conditions. Still, the birth rate has in every year exceeded the 
death rate, the excess varying from 2°40 in 1867 to 12°80 in 
1897. During the period 1862-1899, the population increased 
by 10,000,000. In connection with the decreased death rate, 
the author estimates an annual saving of eight lives per thousand 
in the period 1897-99 as compared with the period 1862-75. 
| Taking account of the influence of the diminished birth rate, 
and assuming that the reduction of the death rate is due to pro- 
gress in checking the spread of infectious diseases, it is considered 
that at least 200,000 people have been effectively saved from 
death, and that the number of those saved from illness must be 
at least twenty times as great. 
In “‘ Notes on the Geology of the Eastern Desert of Egypt,” 
by Mr. T. Barron and Dr. W. F. Hume (Dulau and Co., 1902), 
there are some interesting remarks on the later physical changes 
Attention is drawn to certain 
“igneous gravels” which in reality are gravels containing in 
places fragments of granite, gneiss and other stones derived from 
the Red Sea hills. They are probably Pleistocene and of earlier 
date than the Nile, as its bed has been cut through them and its 
alluvium overlies them, so that this river could not have begun 
to flow until late Pleistocene times. A study of the raised 
beaches and coral reefs affords evidence of important movements 
which ushered in the present conditions. During the Pliocene 
period, minor fault-valleys were formed, and likewise great 
rifts such as the Red Sea (with the invasion of the fauna of the 
southern seas), the Gulf of Suez and other features. Miocene 
strata afford evidence of the former extension southwards of the 
Mediterranean ; Oligocene strata have not been recognised ; 
while the earlier Eocene strata, preserved here and there 
from destruction by faults, point to the Eocene sea having 
covered the entire area examined. These Eocene strata are 
Londinian in age, but they comprise two series, an upper, 
mainly composed of limestones with nummulites, and a lower, 
of shales and marls. The lower series rests unconformably on 
Upper Cretaceous limestones, which are characterised by 
abundant oysters and. well-marked bone-beds. Certain 
gypseous deposits near the Red Sea have resulted from the 
chemical alteration of Cretaceous and Eocene limestones. The 
Nubian Sandstone, which underlies the Cretaceous limestones, 
is also regarded as‘of Cretaceous (Santonian) age, and it rests 
on smoothed surfaces of Plutonic, volcanic and metamorphic 
rocks, planed down by marine erosion. 
WE have received a copy of a paper by Dr. J. Beard, from 
the Zoologischer Jahrbuch, entitled ‘*The Determination of 
Sex in Animal Development.” 
THE Revue. générale des Sciences of October 15 contains an 
admirably illustrated account of a discourse on. “‘ extinct 
monsters” recently delivered by M. Marcellin Boule in the 
