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‘HE first of the two annual conversaziones of the 
Royal Society was held at Burlington House 
on May 16, when Sir Charles Sherrington and the 
_ officers of the Society received the fellows and guests. 
In the space available it is impossible to deal ade- 
*. eae with all the exhibits, so we propose to group 
em according to subject and to give a brief account 
of some of the items in each group. 
The National Institute of Industrial Psychology 
exhibited some results of the researches it has under- 
taken, among which were curves obtained by Dr. 
G. H. Miles and Mr. Eric Farmer showing the effects 
of encouraging rhythmical movements and of reducing 
needless decisions. Output increased by more than 
35 per cent., despite which the workers spontaneously 
testified to their lessened fatigue. Mr. Eric Farmer 
also demonstrated the reduction of after-images pro- 
duced by using a frosted glass on the miner’s standard 
electric lamp. 
The effect of temperature on the biological action 
of light was illustrated in a demonstration arranged 
by the National Society for Medical Research (Dr. 
23 appeal Hill and Dr. A. Eidinow). Hay infusoria 
wefe exposed in shallow quartz cells to the mercury 
vapourlamp. The quartz cell in each case is attached 
to a glass cell through which water is circulated at a 
given temperature. The lethal power of ultra-violet 
rays is manifested by granulation and loss of mobility, 
and at 20°C. these signs appear in about one-third 
of the time required at 10°C. Mr. H. J. Buchanan- 
Wollaston had an interesting exhibit showing the 
value of markings on herring-scales as a means for 
estimating age and growth rate of the fish. Scales 
from the same fish may have widely differing numbers 
of rings ; those on the outer part of the large scales 
should be read in groups, and the age checked by 
means of dorsal scales and “‘ key-scales.’’ The ages 
deduced are much less than those obtained by Danish 
workers. 
Some developments in microscopy were illustrated 
_by the exhibits of Mr. Conrad Beck and the National 
Institute for Medical Research (Mr. J. E. Barnard, 
‘Mr. John Smiles, and Mr. F. Welch), Mr. Beck 
showed a new illuminator for opaque objects, con- 
sisting of an aplanatic ring of glass silvered on the 
back surface, which enables a short focus reflector of 
great light intensity to be used with powers as high 













as 4 mm, (1/6). 
he Director, Royal Botanic Gardens, Kew, 
showed specimens of efwatakala grass (Melinis 
minutifiora P. Beauv.), a valuable pasture grass in 
the tropics, reported to be repugnant to the tsetse 
fly. This property appears to be due either to the 
aroma of the oil exuded by the hairs on the leaves 
or to its stickiness. In another exhibit, species of 
Psychotria, Pavetta, and Kraussia (Rubiacex) with 
nodular swellings in their leaves, due to the presence 
of colonies of bacteria, were shown. The bacterium 
can assimilate free nitrogen from the air. The 
Physical Department, Rothamsted Experimental 
Station, Harpenden (Dr. B. A. Keen, with Mr. E. M. 
Crowther and Mr. W. B. Haines), had exhibits dealing 
with flocculation and deflocculation in soils. An 
automatic electrical balance, devised by Prof. Oden 
and Dr. Keen, gives a continuous time record of the 
accumulating weight of deposit from a soil suspension. 
Analysis of the time-weight curve thus obtained gives 
an indication of the type of soil. 
Messrs. J. J. Griffin and Sons, Ltd., showed a 
“ Boys” integrating and recording gas calorimeter 
_ which has already been described in Nature (August 
19, 1922, vol. I10, p. 251). Dr. Hele-Shaw exhibited 
NO. 2795, VOL. 111] 
May 26, 1923] NA TURE 721 
wt The Royal Society Conversazione. 
his stream-line filter, which causes the fluid which 
has to be filtered to flow with stream-line motion. 
This is done by forcing the fluid down holes drilled 
through parallel sheets of paper impervious to the 
fluid itself ; the fluid escapes by passing between the 
sheets of paper. Dirty water and oil, and water 
containing a dye, were all freed of foreign material. 
Among the exhibits of the International Western 
Electric Company was a low voltage kathode ray 
oscillograph. The instrument consists of a glass tube 
in which a kathode ray is generated between a hot 
filament kathode and a small tubular anode. The ray 
is rendered visible by striking a fluorescent screen at 
the end of the tube. It is deflected on passing 
between two pairs of plates to which two alternating 
potentials are applied. The fluorescent spot then 
traces out a curve which is a graph of the relation 
between the two potentials. Among the exhibits of 
the Research Department, Woolwich, was an appara- 
tus for the detection of feeble X-ray beams by smoke 
clouds. A smoke cloud, having a flat top, is produced 
in a small chamber, below an electrode maintained 
at a potential of about 400 volts. Evena feeble X-ray 
beam striking the cloud produces ions, some of which 
attach themselves to the smoke particles, and the latter 
can be seen rising from the top of the cloud. A chrono- 
graph for use with a photographic recorder was also 
shown. Time intervals of 1/1000th second are recorded 
on a moving cinematograph record by interrupting the 
spot-light from an Einthoven galvanometer by means 
of a wheel with 20 radial vanes, which is made to 
revolve at 50 revolutions per second. The accuracy 
of the recorder for long or short time intervals is at 
least 1/10,o00th second. 
Mr. S. G. Brown exhibited a frenophone, a form 
of loud-speaking telephone, in which the sound is 
amplified by friction. The telephonic current con- 
trols the pressure of a small cork pad upon a revolving 
glass disc, and the variations in the resulting frictional 
drag are applied to the telephone diaphragm of the 
instrument. Very clear articulation is produced. In 
an exhibit by the Cambridge and Paul Instrument 
Co., Ltd., a phonic motor driven by a tuning-fork 
controls a contact on a circular rheostat, which is 
rotated by a direct-current motor. If the latter gains 
or loses speed relatively to the phonic motor, the 
rheostat automatically synchronises the motor with 
the tuning-fork. The mechanism was designed by 
Dr. W. Rosenhain. 
Curious as well as interesting were the exhibits of 
Mr. Harrison Glew, who showed a bar magnet of 
cobalt-steel floating above the opposed poles of a 
fixed magnet (NATURE, May 12, p. 669), and of Mr. 
E. Hatschek, who had a number of permanent 
“hanging drop” and vortex forms produced by 
running gelatin sol into suitable coagulating solutions, 
while the device of Mr. D. Northall-Laurie, showing 
photomicrographs of crystals in colour mounted to 
show changing tints, was very striking. Colour photo- 
graphs (Paget process) are taken of the subject, and 
the slides are constructed to allow the viewing screen 
to be moved across the transparency. The tint of 
the slide then changes from green through various 
intermediate colours to red, just as the tint of crystals 
examined under a microscope by polarised light can 
be made to change. There were other specimens and 
pieces of interesting apparatus, such as that shown 
by Messrs. Adam Hilger, Ltd., for optical research, 
but a fuller account cannot be attempted. 
During the evening, Sir Richard Paget lectured on 
the reproduction of vowel sounds, and Mr. Walter 
Heape on the Heape and Gryll rapid cinema machine. 
