260 
extending perhaps beyond the orbits of the asteroids. 
In fact, the difference in the densities of the inner 
and outer planets and the sun, and the fact that 
practically all rotations and revolutions are in the 
same sense, suggest that our solar system once con- 
sisted of a sun and the outer planets, all having a 
very low density, and that on passing through a 
cloud of heavy meteoric matter, the density of the sun 
was slightly increased, and the inner heavy planets 
created; but it is impossible here to go into the 
details of these interesting questions. 
As regards the nearer evidence of the earth’s age to 
be sought for in the sedimentary rocks, no notice 
seems to have been taken either of the time required 
for the innumerable raisings and lowerings of level 
which certainly occurred during the coal periods 
or of the time which it must have taken 
to tilt horizontal strata through go° and more. 
Thus Japan is. being tilted at the rate of 
about 0-5” per century, and if this tilting rate were 
steadily maintained in one locality, which is highly 
improbable, the Japanese strata would stand 
on end like our Cambrian strata in about forty million 
years’ time. Yet a few such tiltings were completed 
before some of our oldest strata were formed and over- 
thrusts suggest a still greater antiquity for the age 
of sedimentary rocks. C. E. SrROMEYER. 
* Lancefield,’”’ West Didsbury, April 26. 
Man’s True Thermal Environment. 
IN connection with Prof. Leonard Hill’s very 
interesting and instructive article on ‘‘ Healthy Atmo- 
spheres” (Narure, April 22), perhaps I may be 
allowed to direct attention to a paper which I con- 
tributed to the Journal of the Scottish Meteorological 
Society for 1912, entitled ‘‘On Atmospheric Cooling 
and its Measurement: An Experimental Investiga- 
tion.” In that paper will be found a description of 
an instrument termed a psuchrainometer (Wvuypao= 
I become cold; and petpov=a measure) which traces 
on a moving paper strip, a continuous record of the 
amount of electrical heating needed to maintain at 
blood heat a body freely exposed to the atmosphere. 
This seems to serve much the same purpose as Prof. 
Hill’s caleometer. In the same paper I also gave a 
table of preliminary numerical results obtained by its 
use in conjunction with an anemometer and _ self- 
recording thermometer, and from these data deduced 
an empirical formula giving the rate of cooling (Wp) 
as a function of temperature and wind velocity. 
The question as to whether w could always be thus 
expressed as a function of already existing meteoro- 
logical data can only be settled by a long continued 
series of observations with appropriate instruments, 
in the construction of which I have been engaged for 
some time. If W can be so expressed, then evidently 
there would be no need for a widespread installation 
of special apparatus for its measurements. If, how- 
ever, this hope be disappointed, a new apparatus must 
be placed in the hands of meteorologists, and the simpler 
this is the better. I have now constructed a simple 
psuchrainometer, consisting essentially of a thermo- 
meter furnished with a small heater through which 
a constant current is always passing. This may be 
termed a “constant energy” psuchrainometer, and 
I propose to calibrate it against the necessarily more 
complicated form of ‘‘constant temperature’? psuch- 
rainometer, different patterns of which are described 
both in Prof. Hill’s article and in my paper. 
James Ropert MILNE. 
Physical Laboratory, Edinburgh University, 
April 30. 
NO. 2375, VOL. 95| 
NATURE 
[May 6, 1915 



THE AUSTRALIAN ANTARCTIC 
EX PEDITION.} 
Aes most vexed question in antarctic geo- 
graphy has been the nature of the region 
west of South Victoria Land. D’Urville and 
Wilkes, who explored that region in 1838 and 
1839, reported land in so many localities that it 
has been generally believed that their tracks 
skirted a continuous ice-covered and_ ice-barred 
land. Ross, however, sailed across the site of 
some of the land reported by Wilkes, and later 
explorers have had the same experience. The 
view has therefore often been held that this part 
of Antarctica consists of an archipelago. The first 
material step toward the solution of this problem 
was the sledge journey of David, Mawson, and 
Mackay during Shackleton’s expedition. Their 
journey afforded strong evidence in favour of the 
continuity of the Jand; but this land might end 
far south of Wilkes’s track and be separated from 
it by a fringe of islands. This question has been 
finally settled by the Australian expedition of 
1g1t to 1914 under Sir Douglas Mawson. The 
narrative of its experiences with some indications 
of its scientific results are given in two massive 
and superbly illustrated volumes. 
The expedition’ sailed in the Aurora under the 
skilful command of Capt. Davis, whose soundings 
between Australia and the opposite coast of Ant- 
arctica are themselves of the highest geographical 
importance. Two bases were established in 
Antarctica, the main base in Adelie Land (about 
142°40" E.), and a western base under Wild in 
Queen Mary Land (95° E.); at each of these 
stations elaborate observations were taken, and 
the expedition established on Macquarrie Island 
a wireless station, which should be permanently 
maintained in the interests of Australian meteoro- 
logy. From each of the bases extensive sledging 
expeditions were made to explore the surround- 
ing areas. Wild sledged 4° eastward along the 
northern coast to Queen Mary Land in the hope 
of reaching Knox Land. A second party under 
Dr. S. E. Jones travelled westward to the Gauss- 
berg, and thus reached the field of work of the 
German Antarctic Expedition under Drygalski. 
From the main base in Adelie Land one sledging 
party went eastward to Deakin Bay; a second 
under Bage nearly reached the Magnetic Pole; a 
western party sledged 44° along the coast which 
had been seen by D’Urville. A sledge journey 
eastward over the ice-covered plateau led to one 
of the most tragic of Antarctic adventures, for 
Mertz and Ninnis perished on the journey, and 
only the lucky finding of a food depét enabled 
Mawson to crawl back to his base. 
The journey toward the South Magnetic Pole 
under Dr. Bage was one of the most arduous and 
successful of the sledging expeditions. The party 
reached lat. 70°36/5” S. and 148°10! E., where 
the magnet had a dip of 89°433/ or only 16% 
1‘*The Home of the Blizzard. Being the Story of the Anstralasian 
Antarctic Expedition, 1911-14." By Sir Douglas Mawson. Vol. i. Pp. 
xxx+349. Vol. ii. Pp. xiii+338. (London: W. Heinemann, 1915.) Price 
36s. net two volumes. 

