






























ARY 3, 1923, 
=. 
_ brought together extensive collections. The Hipparion 
_ clays of northern China prove the richest deposits 
‘so far. The north China loess but rarely contains 
fossils. One of the commonest is the egg of a big 
ostrich, Struthiolithus chersonensis. There is also an 
elephant, doubtfully referred to Elephas namadicus. 
No undisputed proof of the existence of Paleolithic 
man has as yet been obtained, nor of any Older 
Neolithic culture. 
_ Inpuction Motors As SYNCHRONOUS MACHINES.— 
In the Journal of the Indian Institute of Science, 
vol. 5, part 4. 37, there is an interesting and useful 
paper by S. V. Ganapati and R. G. Parikh on induc- 
tion motors used as synchronous machines. From 
: point of view of the engineer of the supply station 
large “‘ wattless '’ current taken by induction 
_ motors is a serious drawback to their use, and methods 
are sometimes employed to penalise consumers in 
P oportion to the amount of wattless current they 
m 
sé. The authors have experimented on induction 
otors by supplying their rotors with direct current 
_and thus converting them into synchronous machines, 
They found that they were more unstable than 
wdinary synchronous motors, as a relatively small 
decrease in the exciting current caused them to fall 
out of step. They find also that, for heavy loads, 
s method involves a sacrifice of efficiency and 
a slight diminution of the wattless current. 
¢ is also necessary to adjust the excitation to the 
load and hence it is unsuitable for fluctuating loads. 
The advantages of synchronous operation are only 
pronounced at times of light load. 
_ PositivE AND NEGATIVE VALENCES.—The Recueil 
Pe Travaux chimiques des Pays-Bas, which was 
- founded in 1882 and of which the forty-first volume 
2 just been completed, is now to assume an in- 
_ ternational character, since it has been arranged that 
_ the Recueil will henceforth contain articles in French, 
glish,and German. With this announcement there 
has been circulated a double number for September 
and October 1922, in which this policy has been put 
nto operation. The issue contains the papers read 
at an International Congress of Chemistry held at 
Utrecht on June 21-23, 1922. It includes 14 papers, 
‘of which three are in English, four in French, and 
seven in German. The three Russian authors con- 
tribute two papers in French and one in German, 
while the Swiss contribution also appears in French. 
erhaps the most interesting of these papers is the 
me in which Prof. W. A. Noyes discusses the question 
of itive and negative valences. He puts forward 
; idence of the real existence of oppositely polarised 
atoms the production of an optically active form of 
the diazo compound : 
+N 
ec 
wow 
CH, . CH,. CO, . C,H,, 
L it is almost impossible to find a satisfactory 
explanation of the optical activity except by supposing 
that the two nitrogen atoms differ sufficiently to 
destroy what would otherwise be a plane of symmetry 
‘of the molecule. The question of free radicals is 
also discussed in two papers by Prof. Walden and 
i: of. Schenck. 
_ STRESSES IN BEAMS, RINGS, AND CHAINs.—The 
i bo y members’ lecture to the Junior Institution 
> -o! eers for the year 1922 was delivered by 
\ : . G. Coker, who chose for his subject ‘‘ that 
branch of the elasticity and strength of materials 
_ which deals with the stress distributions in curved 
‘NO. 2779, VOL. 111] 
4 4 
’] 01 
ro! 
Prot. 
NATURE 
161 
beams, rings, and chain links.’ The lecture is 
printed in the Journal of the Institution, Part 6, 
vol. xxxii., and forms a valuable résumé of the 
application of the optical epee of transparent 
bodies to the determination of the stresses in these 
bodies. It is pointed out that in plain stress, all 
materials which fulfil the primary conditions of 
elasticity are stressed in precisely the same manner 
under similar conditions of shape and loading, and 
so the stresses can be found by observation on 
transparent material like nitro-cellulose. The cases 
dealt with are the straight beam subjected to bending 
moment (to show that when the beam is un- 
symmetrical about the plane of bending, the usual 
formula giving the stress in terms of the change of 
the curvature is not correct), discontinuities in 
beams, short beams, beams of constant curvature 
under uniform bending moment (as being of theoretical 
interest), the crane hook, circular rings, elliptical 
link with and without stud, circular link with 
straight sides, and various kinds of piston rings. 
The mathematical treatment is indicated, while in 
two appendices is given in brief the mathematical 
theory of stresses in curved beams (Andrews and 
Pearson) and of stresses in curved links (Pearson- 
Winkler theory). Prof. Coker’s lecture is a record 
of important researches on an important subject, to 
which he and his assistants have made very con- 
siderable contributions. It is of interest to note his 
opinion “‘ that the stress distribution in complicated 
bodies . . . is one which still demands a very large 
amount of study by analysis and experimental 
research.” 
THE Finitistic THEORY OF Space.—The logistic 
mathematicians are very boastful of their claim to 
have solved the paradoxes of Zeno by their new 
definition of infinity as a compact series. Their 
doctrine, however, is not unchallenged. Dr. Pe- 
tronievics in his “ Principien der Metaphysik ’’ has 
put forward the theory of the finiteness crt e number 
of points in space. is argument is set forth from 
the point of view of mathematics, metaphysics, and 
also what he terms hyper-metaphysics, and historically 
it is claimed to be as old as Pythagoras. A clear, 
concise, and easy account of the doctrine is given in 
“Die Lehre vom diskreten Raum in der neueren 
Philosophie,’’ by Dr, Nikola M, Poppovich (Wilhelm 
Braumiiller, Wien und Leipzig, 1922). It is the 
thesis for the doctorate of philosophy awarded by 
the University of Berlin the year preceding the war. 
Dr. Poppovich reviews the whole problem of the 
principle of the continuity and discreteness of space 
from ancient to modern times, The theories fall 
for him into three types. The first he names the 
infinitistic realistic, it includes Bolzano and Cantor ; 
the second, the infinitistic idealistic, includes Leibniz 
and Kant, and in the nineteenth century is re- 
presented by Renouvier; the third is the finitistic 
realistic doctrine of Petronievics. According to this 
last there is a clear distinction between real and 
unreal points. The essence of the doctrine would 
seem to be that the compact series which separates 
two points is not a series of real points in the sense 
in which the two definite points are real. The 
compact series has no other function than that of 
holding the two real points apart. Thus, to take 
our own illustration (if we are rightly interpreting 
the doctrine) the integers 1, 2, in the numerical 
series are separated by an infinite, t.e. a compact, 
series of fractions, but this series is unreal, i.e. 
imaginary ; it serves the single purpose of preventing 
the two units falling into one identity. the theory 
leads Dr. Petronievics to affirm the absoluteness of 
Euclidean space. 
