328 
NATO RE 
[NOVEMBER 13, I9I3_ 
5 
arc lamps, and on snow surfaces at a great elevation 
when the absorption of the atmosphere is reduced. 
Snow-blindness and its concomitants are due to this 
cause. Examined by a prism it is seen that by this 
‘‘Spectros” glass all the ultra-violet light is stopped, 
while that in the central portion of the spectrum is 
allowed to pass; there are no absorption bands. 
Microscopists may find the use of various thicknesses 
or prisms of this glass an advantage in their work. 
Pror. A. M. WortuinctTon has contributed a very 
valuable paper on multiple vision with a single eye 
to vol. vi. of the Proceedings of the Royal Society 
of Medicine. The cause of monocular diplopia and 
polyopia has hitherto been considered rather obscure 
by ophthalmologists, who have usually contented 
themselves with the view of Donders that ‘the 
polyopia arises from the fact that each of the more 
or less regular sectors of which the eye is structurally 
built up forms a separate image.’’ This explanation 
fails to cover the fact that even widely separated 
images of an object seen out of focus are at once 
accurately superposed, when the error is corrected 
by means of a suitable lens (spherocylindrical if neces- 
sary. The main value of the paper is the produc- 
tion of direct experimental evidence that similar mul- 
tiple images are formed on a photographic plate when 
the lens of the camera is obscured by a spattering 
of black plasticine. This is a confirmation of Ruete’s 
explanation in 1853 that polyopia was due to irregu- 
larities and opacities on the surface of the lens. Prof. 
Worthington has succeeded in obtaining a well-marked 
polyopia, or rather a multiude of images, by putting 
a thin layer of a dilute solution of canada balsam 
on a clean lantern slide. This is a very fair repre- 
sentation of the normal irregularities on the anterior 
capsule of the lens of the eye, and it will be found 
that, if the object be fine enough and sufficiently 
brightly illuminated. any eye when a little out of 
focus will exhibit this phenomenon, which indeed may 
be considered as a variation of Scheiner’s experiment 
when an object is viewed through a card pierced by 
a great number of pinholes. The illustrations which 
accompany the paper are excellent. 
Tue address of Mr. A. G. Lyster, president of the 
Institution of Civil Engineers, was delivered on 
November 4. Mr. Lyster dealt with the constitution 
of port authorities as affecting the organisation and 
development of ports, a subject to which he brought 
his long experience derived in the port of Liverpool. 
Such authorities should be bodies capable not only 
of bringing special commercial knowledge and sound 
judgment to bear on problems with which they have 
to deal, but also able to take a broad view of their 
responsibilities and to recognise that national and 
imperial, as well as local interests, are involved in 
the successful administration of their charge. The 
ownership and management of docks and harbours 
may be grouped as (a) private, (b) public dock com- 
panies, (c) railway companies, (d) municipal corpora- 
tions, (e) trusts or commissions, (f) governments. 
The constitution of these variously governed ports 
has not been based on any common standard of suit- 
ability; the adoption of a variety of systems has the 
NO. 2298, VOL. 92] 
merit of arriving by experience at a practical deter- 
mination of their relative utility. Mr. Lyster pro- 
largest ports, such as Liverpool, Glasgow, and Dub- 
lin, were under municipal control in their early stages, 
and it was deemed expedient to convert them into 
trusts, or, in the case of London, to sell the City’s 
interest to dock companies. It is difficult to see how © 
the essentials required of a body to manage success- 
fully a port can be obtained under Government con- 
trol. The responsible authorities in this case are 
remote in every sense of the word from those whose 
interests are involved. Under an efficient system 
there ought to be close connection between the 
management and the whole commercial interests of 
the port. The trust system has recommended itself 
to the people of this country as best suited to their 
largest and most important ports. 
WE have received the October number of ‘‘ Lewis’s 
Quarterly List of New Books and New Editions 
added to the Technical and Scientific Circulating 
Library.” It contains the books which have been 
published and added to the library during the months _ 
of July, August, and September. The first part of 
the list is occupied with the additions to the medical — 
side of the library, while in the second, under the 
general heading ‘‘Scientific,’’ will be found those on — 
such subjects as chemistry, engineering, metallurgy, 
motor-cars, technology, &c. Short notes are given 
to the more important works, and the list should be 
useful to students and others wishing to see what 
has appeared during the months included on any — 
subject in which they are interested. 
THE 1914 issue is now available of the ‘Nature 
Calendar,”’ published by Messrs. G. Philip and Son, 
Ltd., at the price of sixpence net. The special notes — 
for the months of 1914 deal with problems of nature- 
study suitable for continuous observation. The 
calendar is eminently adapted for exhibition on the — 
walls of schoolrooms and natural history club-rooms, 
where nature-study is taken up in a practical manner. 
OUR ASTRONOMICAL COLUMN. 
Comer 1913d (WestpHaL).—This very interesting 
periodic comet of 1852 IV. is likely, according to The — 
Observatory for November, to be visible for several — 
months, and that journal publishes an ephemeris up — 
to the middle of January, in continuation of that — 
given by Prof. Kobold. This ephemeris is computed — 
with slightly different elements, and a portion of it — 
is as follows :— ’ 
Greenwich, Midnight. 
R.A, Dec. N. 
i" hi rn hes " ; 
Noy. 17 20 31 51 34 8 
21 2 28 36 20 
25 33 54 38 25 
29 20 35 56 40 27 
The comet is about magnitude 8-7, and is situated — 
in the constellation of Cygnus. wt 
EUROPIUM IN STELLAR SPECTRA.—In this column for 
October 2 reference was made to the striking varia- 
tions in the spectrum of « Canum Venaticorum dis- 
covered by Prof. Belopolsky. The full account of his 
