; ApRIL 28, 1923] 
NATURE 
583 

opposed to the point of view of the great Scandinavian 
mycologist Eriksson, who has assumed that the fungus 
_ must persist through the life-cycle of the host plant 
as an undetectable protoplasmic contamination, 
“mycoplasm,” intermingled with its own living sub- 
stance. 







ARTESIAN WATER IN AUSTRALIA.—In the report 
for 1921 of the Director of Mines and Government 
Geologist for South Australia, there is included a 
useful map of the principal artesian basins of Australia, 
made in connexion with the interstate conference on 
artesian water which met at Adelaide in September 
1921. The map is of special interest in showing the 
isopotential lines or the heights above sea-level to 
which the water will rise. These lines have been 
accurately determined in many parts of the great 
artesian basin, especially in New South Wales and 
Queensland. They are less certain in parts of South 
Australia, but they are sufficiently accurate to show 
the absence of any concealed south-westerly outlet. 
The basin as a whole has marginal intake beds sur- 
rounding it. Fragmental isopotential lines for the 
Murray river basin have been embodied in the map. 
The scale of.the map is too small to allow detail in 
the case of the basins of Willochra valley, Port Pirie, 
Cowell, and Adelaide plains. There is a lack of in- 
formation in the case of the Eucla basin, but from the 
variable salinity of the water it would seem to be 
derived from more than one source in the sandy desert. 
GENERALISED OpticaL LAw.—Part 1 of volume 24 
of the Transactions of the Optical Society contains 
the generalised optical law communicated by Mr. T. 
Smith to the Society in December last and called by 
him the optical cosine law. It includes as special 
cases the law of refraction, the coma sine law, the 
axial displacement and other exact laws of optical 
instruments, and runs thus: If I is the angle of 
inclination of a ray to a chosen fixed direction in the 
object space and I’ the inclination of the emergent 
ray to a chosen fixed direction in the image space, 
then the rays for which cos I= cos I’ +q where p 
and g are constant touch caustics S in the object and 
S’ in the image space, and if S be displaced a small 
distance s along the fixed direction in the object 
space to S, the image caustic S’ will move along the 
_ fixed direction in the image space through a distance 
s’, where n’s’ =nsp and n n’ are the refractive indices 
of the object and image media. The application of 
this generalised law to the construction of a telescope 
aplanatic at all magnifications is given as an illustra- 
tion. 
WIND STEADINESS IN THE UPPER AIR.—To the 
March number of the Meteorological Magazine Mr. H. 
_ Harries contributes some curious facts about the 
flights of toy balloons in “‘ races’’ organised by Major 
MacLulich at Brighton during the summer of 1922. 
On August 23 two balloons were liberated together, 
and next morning they descended in the little village 
of Marcel par Vitrey, Haute Sadne, having travelled 
in company S. 51° E., 295 miles. On September 21 
two others started together in a dead calm, made a 
perpendicular ascent of about 2000 feet, and dis- 
appeared in a cloud. Within 12 hours both dropped 
in the streets of Cassel, Germany, the course and 
distance being N. 85° E., 365 miles, at a rate of 30 
miles an hour. Numerous balloons were sent off on 
September 9, under well-marked anticyclonic north 
wind conditions. The cards of 43 of them were 
recovered within a small area in the north of France, 
nearly all having followed a course between S. 2° E. 
and g 5° E. They had attained an altitude where 
the wind was of gale force, one of the balloons, found 
24 hours after its despatch, having covered 108 miles, 
NO. 2791, VOL. 111] 
at a rate exceeding 43 miles an hour. Of a different 
character were the flights of September 13, the 
balloons being liberated in front of a cyclone approach- 
ing Brighton from the midland counties. The cards 
of 20 were returned, and of these 15 were drawn into 
the cyclone and descended in various places in Kent, 
Essex, Suffolk, Bucks, and Berks—the greater part of 
the circuit of the cyclone. The other five, apparently 
attaining a higher altitude, were caught in a westerly, 
veering north-westerly, current, which carried them 
to north-eastern France. One dropped at St. Ouen, 
Paris, 226 miles distant from another despatched at 
the same time, which descended at Thatcham Park, 
Stowe, Bucks. 
AcTIVE HyDROGEN AND CHLORINE.—In the Pro- 
ceedings of the Science Association, Maharajah’s 
College, Vizianagram, published in December 1922, 
Mr. Y. Venkataramaiah gives an account of some 
further experiments he has made on active hydrogen. 
Hydrogen gas obtained by the action of heat, and of 
water, on sodium hydride, as well as hydrogen gas 
which had bubbled through molten sodium, reacted 
with sulphur in the cold, and therefore contained 
active hydrogen. Similar results were obtained with 
potassium and calcium. Other methods for the 
activation of hydrogen (burning oxygen in hydrogen, 
surface combustion of hydrogen and oxygen on 
platinum, high tension arc in hydrogen, high tempera- 
ture arc in hydrogen, and the passage of hydrogen 
through heated platinum and palladium) are described 
in further papers. In the same journal Mr. Venka- 
taramaiah describes the activation of chlorine, pre- 
pared by heating gold chloride and dried with 
phosphorus pentoxide, by the silent discharge, by 
electric discharges in the gas, by ultra-violet light, 
and by the heat of an electric arc. The gas combines 
with ozone to form Cl,O, with sulphur to form S,Cl,, 
and reacts with benzene in the dark to form C,H,C],. 
THE HERBERT PENDULUM HARDNEss TESTER.— 
Two points to be looked for in a “ hardness’ tester 
are simplicity of operation and results independent 
of the mass and thickness of the specimen. These 
are among the desirable features of a new instrument 
made by Messrs. Edward G. Herbert, Ltd., of Man- 
chester, others being portability and the immunity 
of the specimen from damage due to testing. Thin 
strip, case-carburised steels, minerals, and glazes on 
pottery thus come within the scope of the machine. 
The apparatus consists of an arched casting weighing 
4 kg., surmounted by a curved spirit-level graduated 
from o to 100, It is supported on the specimen by 
a I mm. ball fixed beneath the centre of the arch. 
With the standard setting the instrument has its 
centre of gravity o-1 mm. below the centre of the ball, 
and is thus free to oscillate. “‘ Scale tests '’ are made 
by placing this rocker normally on the specimen and 
tilting it until the level-bubble reads 0. On releasing 
the instrument the graduation to which the bubble 
floats is the ‘‘ Scale Hardness Number ”’ (e.g. glass 97, 
mild steel 30). The recommended ‘“‘ Time tests ”’ 
are made by causing the “ pendulum ”’ to oscillate 
and noting with a stop-watch the time for ten swings. 
Strange to say, while mild steel requires 20 seconds, 
the ‘‘ Time Hardness Number ”’ of glass is 100 seconds. 
Both tests, then, depend upon the degree of indenta- 
tion of the specimen, and a time factor appears to be 
involved. There is good agreement between succes- 
sive determinations. While the instrument detects 
* strain-hardness,’’ it does not appear to indicate 
relative machining properties. The high ranges of 
the time hardness scale may be opened out by raising 
the centre of gravity of the “ pendulum,” and 
altogether the system presents many important 
possibilities. 
