May 23, 1912] 
NATURE 309 
results. 
of 3-4 ft. diameter on a lantern screen. 
Until the advent of a really rapid and satisfactory 
bleach-out paper, there is no possibility of recording the 
photograph on paper in colours, and since they can only 
be viewed in or by means of the camera itself, and 
the latter (which costs somewhere about 6o0l. at pre- 
sent) will always be a somewhat expensive apparatus, 
even if the optical and mechanical parts can be further 
simplified, the process is scarcely one that is likely to 
become general. That indeed was recognised from 
the start of the experiments. Nevertheless, given the 
camera, the process is undoubtedly a simple method 
of colour photography to work, and this, together 
with its true colour rendering and the many interest- 
ing and quite novel effects to which it lends itself, 
will, it may be hoped, encourage plenty of other 
workers to take it up, besides those who may be 
disposed to experiment with it from the point of view 
of its scientific interest. 
THE FORTHCOMING OPTICAL 
CONVENTION. 
40 HE issue of a programme of business by the com- 
mittee of the Optical Convention, which is to 
meet in London on June 19-26 next, marks the 
entrance of this undertaking upon a new stage in its 
development. The idea of an optical convention is 
not new—in fact a meeting, the first of the kind, was 
held in London in 1905, and it is out of that gather- 
ing that the present proposal has grown. 
mittee has secured support of a substantial kind in 
the form of a guarantee fund, which puts the under- 
taking on a secure financial basis and will enable 
the catalogue and volume of Proceedings to be pro- 
duced. 
Underlying the whole scheme of the Optical Con- 
vention is the fact that optical appliances in one form 
or another are familiar, at least as tools, to every- 
body. This circumstance, and the 
scientific problems which present themselves for solu- 
tion in the manufacture of optical instruments, give 
to optical manufacture its special place in the view 
of scientific men at large and of those leaders of 
thought who occupy themselves with the realities of 
the public weal. It is therefore by no means so sur- 
prising as it is pleasant to find that the Board of 
Education on one side and the scientific societies on 
the other are furthering the scheme and assisting to 
bring the pian of an optical convention to a successful 
issue. 
Another aspect of optical work is its national 
importance. It is probably not realised, even. by men 
who are fairly familiar with the developments of 
applied physics, how the progress of manufacture is 
dependent on the provision of the special optical 
and scientific instruments required at each stage of 
its development.  Field-glasses, gun-sights, range- 
finders, and numerous other purely optical instru- 
ments are absolutely essential in the equipment of 
any fighting force at the present day, and it is vital 
to our national interests that we should have, within 
The com- | 
interest of the | 
The pictures may also be projected in a size ! 
our own borders, the means of producing such instru- | 
ments in sufficient quantity for the use of our sailors 
and soldiers. 
The experiment of holding the exhibition in con- 
nection with this Convention in the buildings of the 
Science Museum at South Kensington will be 
observed with considerable interest, no doubt, by the 
officers of the Education Board, and certainly by the 
scientific public. Some years ago, when the Science 
Museum was much less completely organised than at 
present, a departmental committee was appointed to 
NO. 2221, VOL. 89] 
consider its organisation and to report upon the 
improvements that might be made. Among the pro- 
posals which commended themselves to that com- 
mittee was a suggestion that an empty hall should 
be built, as part of a reconstructed museum, which 
might be available for purposes of this kind. That 
proposal is, no doubt, receiving the attention of the 
authorities at the present time in connection with 
their rebuilding plans, and it will be of value to 
them to be able by this experiment to make them- 
selves practically acquainted with the working of such 
an arrangement. The Art Department at South 
Kensington already possesses accommodation of this 
kind in the unoccupied North Court of the Victoria 
and Albert Museum. If such a building is provided 
in connection with the Science Museum, with suitable 
equipment and under proper regulation, it may, we 
think, prove to be of very great value in establishing 
and developing a fruitful connection between scientific 
work and the practical aims of the industrial and 
manufacturing community. 
Attention may also be directed to the very interest- 
ing loan collection of optical instruments which is to 
be exhibited. This loan collection cannot but be full 
of interest, not only to the student who desires to see 
how any particular instrument has grown by 
successive developments to its present stage of 
efficiency or otherwise, but also, as is often the case, 
it may contain the germs of still further discoveries 
which may yet have to be worked out by the efficiently 
trained minds of our men of science and manu- 
facturers. 
The committee of the Optical Convention has, as 
we are glad to see, realised that the establishment 
of such relations in their particular departments ought 
to be a principal object of their undertaking. From 
the provisional programme, it appears that the scien- 
tific societies in their corporate capacity will take a 
prominent part in this Convention. We observe that 
the Physical Society, the Royal Astronomical Society, 
the Royal Photographic Society, and the Optical 
Society have all arranged for joint meetings with the 
members of the Convention, and that their several 
presidents will be presiding at these meetings in the 
character of vice-presidents of the Convention. 
This close connection of the leading scientific socie- 
ties, having special interests in optical science, with 
the Convention is not the only way in which the 
interest of the scientific public is to be manifested and 
utilised. The scheme of operations comprises a some- 
what elaborate plan for making the work of the Con- 
vention subservient to the practical aim of improving 
the design and construction of optical instruments. 
With this object, a highly qualified committee, 
announced under the name of the cooperation com- 
mittee, has been organised. Its members are all 
very distinguished men, but it is not to their initiative 
that the Convention trusts for suggestions of the lines 
along which improvement ought to move. : A schedule 
of inquiries, which has been very extensively circu- 
lated during the last few weeks, will, through one or 
other of the learned societies of London and_ the 
Provinces, have come into the hands of most of our 
readers. It is intended to elicit the expression of 
private and personal opinion by all users of optical 
instruments. That is substantially equivalent to say- 
ing of all who are engaged in exact scientific work. 
These inquiries are intended to produce not so 
much suggestions for improvement as suggestions of 
existing defects and desiderata. The committee 1s’ to 
be informed what it is that the users of optical instru- 
ments desire. From the material so supplied it will 
draw up a report in which it may be presumed that 
the matter of value communicated in answer to this 
