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referred to the Report of the Royal Commission on Secondary 
Education, and the remarkable unanimity with which it had 
been received by educationists. (For a criticism of the Report 
from the scientific side, see NATURE, vol. liii. p. 79.) The 
bodies for which he spoke approached the subject especially 
from the point of scientific and technical education of the 
country. It is an acknowledged fact that the higher technical 
education of the country suffers from the lack of suitable pre- 
paration in the secondary schools, and that little can be hoped 
for in the way of systematic and advanced technical instruction 
until a basis of secondary education, such as has long existed in 
continental countries, has been established. Fortunately this 
organisation, for which Sir Henry Roscoe pleaded on behalf of 
the deputation, is unaccompanied by many of the difficulties 
which surround the subject of primary education, and, therefore, 
in this case Parliamentary unanimity in securing the great bene- 
fits which such a secondary system would confer upen the country 
might be expected. No detailed statement was made as to the 
form which legislation should take, but Sir Henry Roscoe pointed 
out that the most important recommendations of the Royal 
Commission are, in the first place, the establishment of local 
authorities, consisting of not smaller areas than counties and 
county boroughs, and, in the second place, of a central authority, 
chiefly of an advisory character. After several other members 
of the deputation had spoken, the Duke of Devonshire said that 
the Government hoped to deal with the better organisation of 
secondary schools in the next session of Parliament. It is in- 
tended to follow, generally speaking, the lines which were 
indicated in the proposed measure of last year. 
SOCIETIES AND ACADEMIES. 
LonpDoNn. 
Physical Society, November 27.—Prof. Riicker, Vice- 
President, in the chair.—The President (Captain Abney) de- 
scribed and exhibited some apparatus for giving diagrams of the 
efficiency of a photographic shutter. In addition to the 
**speed ” of a shutter, which is concerned with the interval (T) 
between the moments when the shutter admits the fs¢ and Zast 
rays of light, it is most important to know the efficiency of the 
shutter. The efficiency may be defined as follows: Let x 
represent the portion of the available aperture of the lens ex- 
posed by the shutter at a time ¢, and let X be the total available 
aperture. Then if the shutter were perfectly efficient, z.e. if the 
whole of the aperture were efficient during the time T, the 
quantity of light admitted would be proportional to XT. In 
other cases the quantity of light admitted will be proportional 
i mid : 
to | xdt. ence the efficiency is 
0 
The apparatus employed by the author consists of a slit placed 
near the shutter, so that the length of the slit is at right angles 
to the direction of motion of the shutter, and a lens by means 
of which an image of the slit is thrown on to a rotating drum or 
plate. The slit, when the shutter is open, is illuminated by the 
light of an arc lamp, a condensing lens being employed. In order 
to obtain a time scale two devices have been employed. In one 
of these a spoked wheel is rotated at a known speed so that 
each spoke, as it passes, momentarily cuts off the light. In the 
other arrangement a small lens, attached to the prong of a 
tuning-fork,throws a small spot of light on to the rotating drum, 
and thus gives a wavy line. Bromide paper or celloidin films 
are employed to record the diagrams. If the shutter were per- 
fectly efficient, the diagram would consist of a rectangle crossed, 
if the rotating wheel is used, by a number of white lines, caused 
by the interruption of the light by the spokes of the wheel. 
These lines give a time scale by which the speed of the shutter 
can be calculated. The author showed a number of diagrams 
taken by the apparatus and illustrating the behaviour of different 
shutters under varying conditions. In one of these the rebound 
of the Shutter at quick speeds is clearly shown by each of the 
principal diagrams being followed by a small auxiliary one 
Prof. Perry said he supposed that what was required 
Was some method of showing the motzon of the shutter. 
Mr. Boys suggested that the efficiency might be defined as the 
ratio of the area of the actual diagram to that of the rectangle 
NO. 1414, VOL. 55] 
having as base the time between the commencement and end of 
the exposure. Mr. Inwards asked if the author had made any 
experiments to determine the amount of shake communicated to 
the camera by the motion of the shutter. Prof. Perry said what 
was required was an exceedingly light shutter that got up a 
great speed before it reached the aperture. The author, in his 
reply, said he had investigated the question of the shake due to 
the movement of the shutter. He considered that the amount 
of this shake depended upon the extent of the movement of the 
centre of gravity of the shutter. With a small stop the Thornton- 
Pickard shutter fulfilled Prof. Perry’s requirements. The ex- 
periments have shown that the exposure does not always vary as 
the square of the aperture, on account of the small efficiency of 
some shutters for oblique rays. Thus in one case, by doubling 
the aperture, you only increase the light threefold. 
Royal Meteorological Society, November, 18.—Mr. E. 
Mawley, President, in the chair.—Mr. W. Ellis, F.R.S., gave an 
account of the Proceedings of the recent International Meteoro- 
logical Conference, which was held at Paris, from September 
17 to23. The Hon. F. A. Rollo Russell read a paper on haze, fog 
and visibility. | Haze is most prevalent when the wind is from the 
north-east, and is due probably to excess of dust brought about 
by conflicting currents. The causes of fog are to a great extent 
the same as the causes of haze, although radiation in certain 
states of the air and ground playsa more conspicuous part. 
The main cause of fog is mixture of airs of different tempera- 
tures ; and the attainment of a size of water particle so much 
larger than in the case of haze is due to suddenness of mixture, 
greater humidity, or greater differences of temperature. The 
conditions favourable to visibility are dryness of the air near 
the ground level, uniformity of temperature and moisture, 
radiation below the mean, steady and homogeneous © winds 
through a great depth of the atmosphere, approximation of the 
temperatures of sea ana land, and a number of dust particles 
less than the mean. 
PARIS. 
Academy of Sciences, November 23.—M. A. Cornu inthe 
chair.—On some properties of uranic rays, by M. H. Becquerel. 
The rays emitted by uranium and its salts have some properties 
in common with the X-rays, but differ from them in being 
reflected and refracted like light. Even after eight months in 
complete obscurity, this radiation from uranium and its salts 
remains unchanged. The property of discharging an electrified 
body, which iscommunicated to a gas by exposure to the X-rays, 
or by transmitting electric sparks through it, isalso possessed by 
air which has passed over uranium in the dark.—Decimalisation 
of the hour, by M. Bouquet de la Grye.—Theoretical study on 
the pitching of submarine vessels, by M. Leflaive. An investi- 
gation of the relations between the displacement, speed, and 
depth under water ; the pitching is also studied, and the results 
displayed graphically.—On a particular case of the motion cf 
liquids, by M. E. Fontaneau.—Euclid’s postulate, considered 
as a property of three-dimension space, by M. G. Morosov.— 
Observations on the new Perrine Comet (1896, November 2) 
made at the Observatory of Algiers, by MM. Rambaud and Sy. 
—On algebraic curves of constant torsion, by M. Eugéne Fabry. 
—On an application of the theory of continued groups to the 
study of the singular points of linear differential equations, by 
M. F. Marotte.—On the singularities of the equations of 
dynamics, and on the problem of three bodies, by M. P. 
Painlevé —On the movement of a solid in an infinite liquid, 
by M. R. Liouville. —On the distribution of deformations in 
metals submitted to stresses, by M. George Charpy. A continua- 
tion of the discussion with M. Hartmann.—Discharges by the 
Rontgen rays; influence of temperature and pressure, by M. 
Jean Perrin. It is found that for the same gas, at a constant 
temperature the quantity of electricity lost per unit mass of gas 1s 
independent of the pressure, and proportional to the absolute 
temperature. It is noteworthy that according to the kinetic 
theory of gases the energy possessed by a molecule is 
also independent of the pressure and proportional to the absolute 
temperature.—Illusions which accompany the formation of 
penumbra, and applications of these to the X-rays, by M. G. 
Sagnac. No conclusions can be drawn from any peculiarities 
exhibited by shadows, without taking into account the extent 
and form of the source, the relative lustre of its different points, 
the form and position of the opaque body, and the photometric 
properties of the retina or photographic plate. The precaution 
should always be taken of replacing the Rontgen tube, in any 
