368 
WATORE 
[lEBRuARY 18, 1897 
the centre of the disc in sucha manner that the unpre- 
pared face of the disc may rest upon the pin’s head (a 
lady’s hat-pin is better for the purpose than a small one) ; 
the pin-hole must be sufficiently large to allow the disc 
to turn freely. Holding this arrangement by the pointed 
end of the pin (which should be directed vertically up- 
wards) above a design in black lines upon a white ground 
—any drawing, writing, or printing will do, provided that 
the lines are not too thick—the observer spins the disc 
by striking its edge tangentially with his finger in the 
direction such that the gap follows the black portion, and 
is followed by the white portion of the disc. If the disc 
makes five or six turns per second, and the before- 
mentioned precautions as to illumination and shadows 
are duly observed, the black lines of the design, seen 
through the opening in the disc, will appear bright red, 
and, owing to persistence, the impression will be almost 
continuous. 
When the disc is made to turn in the reverse direction, 
the lines appear to become (subjectively) blue instead of 
red. This appearance is partly, if not altogether, illusory. 
Careful observation shows that the subjective blue tint is 
not formed upon the lines themselves, which remain 
black, or rather grey, but upon the white ground just out- 
side them. This and other experiments detailed in the 
paper indicate that when a dark patch is suddenly formed 
upon a bright ground, the patch appears for a moment to 
be surrounded externally by a blue border. 
We have then to account for the two facts, that in the 
formation of these transient coloured fringes, the red 
originates in a portion of the retina which has not been 
exposed to the direct action of light, while the blue 
originates in a portion which is subjected to steady 
illumination. The effects must, I think, be attributed to 
sympathetic affection of the red nerve fibres. When the 
various nerve fibres of the Young-Helmholtz theory are 
suddenly stimulated by ordinary white or yellow light of 
moderate intensity, the immediately surrounding red nerve 
fibres are for a short period excited sympathetically, 
while the violet and green are not so, or in a much less 
degree. And, again, when light is suddenly cut off from 
a patch in a bright field, there occurs an insensitive 
reaction in the red fibres just outside the darkened patch, 
in virtue of which they cease for a short time to respond 
to the luminous stimulus, in sympathy with those inside 
the patch. The green and violet fibres, by continuing to 
respond uninterruptedly, give rise to the sensation of a 
blue border. There is reason to believe that with intense 
illumination, such as sunlight, these effects are reversed, 
the sympathetic affection of the red fibres being in such 
case less than that of the green and violet instead of 
greater. 
The above-mentioned are a few among many curious 
phenomena which exhibited themselves in the course of 
my experiments. It appears probable that a careful 
study of the subjective effects produced by intermittent 
illumination would lead to valuable results, tending to 
clear up many doubtful points in the theory of colour 
vision. : SHELFORD BIDWELL. 
A NATIONAL PHYSICAL LABORATORY. 
ARSE Marquis of Salisbury received at the Foreign 
Office on Tuesday a deputation of representatives of 
science who asked the Government to establish a national 
physical laboratory at a cost of £30,000 for buildings, 
and £5000 a year for maintenance. The Zimes gives 
the following report of the proceedings. 
The deputation consisted of Lord Raleigh, Lord Lister, Sir 
John Evans, Sir Douglas Galton, Sir Henry Roscoe, Sir 
Andrew Noble, Prof. W. G. Adams, Prof. W. Chandler 
Roberts-Austen (Iron and Steel Institute), Prof. W. E. Ayrton, 
Mr. J. Wolfe Barry (President of the Civil Engineers), Prof. 
NO. 1425, VOL. 55 | 
R. B. Clifton, Prof. G. H. Darwin, Mr. Francis Galton, Mr. 
R. T. Glazebrook, Prof. W. M. Hicks, Dr. J. Hopkinson, 
Prof. J. V. Jones, Prof. John Perry, Mr. W. H. Preece, Prof. 
William Ramsay, Prof. A. W. Riicker, Mr. Robert H. Scott 
(Meteorological Office), Mr. W. N. Shaw, Mr. J. Wilson Swan, 
Prof. Silvanus Thompson, Prof. W. A. Tilden, Prof. Michae} 
Foster, and Mr. G. Griffith, Secretary of the British Associa- 
tion. 
Lord Lister said it fell to his lot to introduce the deputation, 
as being President of the British Association, with which the 
idea of a national physical laboratory originated, and also of 
the Royal Society, which took an equal interest in the matter. 
Lord Kelvin desired him to say that he was unavoidably absent ; 
he was in full sympathy with their object, and would have been 
present had it been possible. 
Prof. Riicker said the scheme consisted of two parts, which, 
although closely connected, must be regarded as separate. The 
first was the proposal for the establishment of a national 
physical laboratory, and the second was a suggestion of a par- 
ticular method for giving effect to it. There were certain types 
of physical investigation which were too laborious and lengthy 
to be undertaken by individuals or by the staff of an institu- 
tion the primary duty of which was to teach, but which, on the 
other hand, were too closely connected with the advancement of 
knowledge and with research to be undertaken by the staff of a 
Government department. Of these types, the first was the in- 
vestigation of slow changes in the properties of matter which 
persisted through long periods of years. Lord Kelvin had 
made a beginning in the investigation of these in his laboratory 
at Glasgow, but it was not too much to say that, although the 
properties to be investigated might prove to be of great im- 
portance both to scientific theory and to industry, very little was 
known about them at present, or was likely to be known, except 
by an organised effort such as they now suggested. The second 
task they wished to undertake was the testing and verification 
of instruments useful alike to industry and research. Something 
had been done in this country to meet this want. Standards 
of various kinds were in charge of the Standards and Electrical 
Departments of the Board of Trade, but the work which they 
proposed had a wider scope than that of either of those most 
useful departments ; and the institution which in this country 
most nearly approached the ideal at which they were aiming 
was the Kew Observatory. But the permanent endowment of 
Kew amounted to only £447 per annum, derived from a bequest 
of the late Thos. Gassiot. Kew was the central observatory of the 
Meteorological Council, where meteorological instruments of all 
sorts, photographic lenses, compasses, and many other things 
were tested and verified ; and in the last two years the average 
number of instruments per annum submitted to investigation had 
exceeded 21,000. Paris was the seat of the International Bureau 
of Weights and Measures; and some ten years ago the 
Physikalisch-Technische Reichsanstalt was founded near Berlin 
to carry out work of the type which he had just described. 
Like Kew, it received a private benefaction the gift of the late 
Dr. Werner Siemens, but this had been largely supplemented by 
the German Government. At Kew they had to thank the State 
for the site and the use of an old building. In Germany new 
buildings had been provided, at the cost of about £200,000, and 
the annual outlay upon the Reichsanstalt amounted to £15,000. 
The researches carried out, both in Berlin and in Paris, had in 
the comparatively short space of ten years produced remarkable 
results. To give one instance :—Mecurial thermometers were 
subject to errors which made them very difficult to use for 
accurate work. Researches on glass carried out in these foreign 
laboratories resulted in the discovery of a material free from 
many of the objections which might be urged against ordinary 
glass, and a prolonged study of the thermometer resulted in 
increasing the accuracy of mercurial thermometers five-fold. As 
a consequence of this no high-class mercurial thermometers 
were now made in this country, and we had to send abroad for 
them ; in fact, at Kew itself our thermometric standards were a 
series of instruments which had come from Paris, and would have 
to be sent there to be verified if any accident or careless handling 
should throw a doubt upon theirindications. At the Reichsanstalt 
there was a large department specially devoted to the investiga- 
tion of problems useful to industry, and it was understood that 
instrument-makers, when in doubt as to the best construction of 
some new and delicate instrument, could obtain help from the 
experts in the National Laboratory. They were very anxious, 
therefore, that at Kew, or elsewhere, an institution should be 
