JANUARY 22, 1914] 
NATURE 
595 
MEMORIAL TABLET TO LORD LISTER. 
TABLET in memory of the late Lord Lister was 
unveiled by Lord Rayleigh at King’s College, 
London, on January 14. The unveiling was preceded 
by an impressive ceremony in the chapel, among those 
present being Dr. Herringham (Vice-Chancellor of 
the University), Sir Rickman Godlee (president of the 
Royal College of Surgeons), Sir William Crookes 
(president of the Royal Society), Sir Henry Miers 
(principal of the University), Dr. Caldecott (Dean of 
King’s College), Sir St. Clair Thomson, Prof. Halli- 
burton, Prof. J. M. Thomson, Sir David Ferrier, Sir 
John Rose Bradford, and Mr. and Mrs. J. J. Lister. 
Lord Rayleigh expressed his pleasure at thus being 
able to pay a small tribute to the memory of Lister, 
under whom he had been privileged to serve for.a time 
at the Royal Society. It is now a commonplace that 
by his advances in surgery he had saved more lives 
than Napoleon had destroyed. Lister, in addition to 
his extreme modesty, was always ready to acknow- 
ledge obligations, and delighted his French colleagues 
by his generous insistence that his work was a 
natural development of that of Pasteur. 
Lord Rayleigh was followed by the Vice-Chancellor 
of the University, Dr. Herringham, who pointed out 
that Lord Lister, at the invitation of King’s College 
Hospital, gave up the chair he held at Edinburgh. 
Dr. Herringham expressed the wish that such trans- 
lations were more common, for they conferred honour 
not only on those translated, but also on the institu- 
tions from which they emanated. 
Sir Henry Miers, Prof. Halliburton, and Dr. Calde- 
cott also spoke briefly. 
The tablet, which has been erected in the corridor 
outside the chapel, bears the inscription :— 
“In affectionate and respectful memory of Joseph, 
Baron Lister, F.R.S., O.M., Professor of Clinical 
Surgery in King’s College from 1877-1892, and for 
many years consulting surgeon to the King’s College 
Hospital, Member of the Council and Life Governor 
of the College, this tablet is erected. His name will 
be handed down to posteritv as the founder of anti- 
septic surgery, one of the greatest discoveries in 
history and a source of inestimable benefit to 
mankind.” 
THE “DAVON” MICRO-TELESCOPE. 
ESSRS. DAVIDSON AND CO. have recently 
produced a ‘‘micro-telescope,”’ an instrument 
which is essentially a microscope of ordinary con- 
struction carrying a short focus telescope objective 
and tube below the stage. It may here be remarked 
that the ordinary terrestrial telescope with erecting 
eyepiece is nothing more than an object-glass, and a 
microscope, for an erecting eyepiece is nothing more 
than a microscope of low power. This is at times of 
great use in the workshop or laboratory, where a low- 
power reading microscope may be wanted in a hurry, 
but it is not everyone who remembers that a pocket 
telescope contains within itself this instrument also. 
While, therefore, the micro-telescope and the 
ordinary telescope with erecting eyepiece have the 
same sequence and function of lenses, and each gives 
an erect image, yet in proportions and practically 
the micro-telescope is a very different thing. 
The triple objective in the micro-telescope, though of 
only 53 in. focal length, instead of the usual 8 or 9g in., 
successfully withstood the following severe test. At 
a distance of a rod, pole, or perch and a half, and a 
vard and a quarter (which works out as 342 in.), a 
Bellows French Dictionary could be read perfectly 
and with a §% in. microscope objective a circle of 
NO. 2308, VOL. 92] 
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3% in. in diameter could be seen at once all in 
focus and with no sign of colour. As a 
more severe test a number of groups of artificial 
double stars, made by small needle-holes in tin 
foil, of which the closest group were all separated by 
1/100 in. centre to centre, were set up at the same 
distance, and all were clearly double stars as seen in 
the micro-telescope, clear, sharp, and without colour, 
but with the first diffraction ring clearly showing. 
These stars subtended centre to centre an angle of 
almost exactly 6" of arc, and as the needle-holes were 
not geometrical points, this test shows that the object- 
glass was up to the optical limit imposed by the size 
of the wave-length of light. 
Some crumbs were then placed on the floor at a 
distance of four yards, and strongly illuminated, and 
the microscope with a 1 in, object-glass focussed 
on the crumbs. Presently some mice came 
out, and made themselves at home with the 
crumbs. The mice could be examined at this dis- 
tance without their being aware of it so well that 
individual hairs were easily visible and about half a 
mouse was in the field of view. In point of size it 
appeared about the same as a beaver within a foot or 
two. The magnifying power was measured and found 
to be 42. 
A plane mirror silvered on the front face is provided 
to be clipped on in front of the telescope objective, so 
that objects may be examined without tilting the 
micro-telescope to an inconvenient angle. ‘This has 
the two motions necessary to bring an object into the 
field of view. The double-star test showed that the 
mirror interfered slightly with the perfection of the 
image, but not to such an extent as to be noticeable 
except with so severe a test. A more serious difficulty, 
however, is that of finding an object when seen in this 
way. It would be easy enough with the moon, for 
instance, and perhaps with a bright planet like Venus 
or Jupiter, but it would probably require some practice 
to find such a star as B Cygni. 
A further attachment is provided by means of 
which the microscope tube is replaced by a camera 
so that either microscope photographs may be obtained 
if the telescope element is replaced by a substage 
illuminator, or if the telescope fitting is in its place 
the combination enables telephotographs to be taken; 
some of these submitted by the makers show that in 
this domain also excellent results are possible. 
Altogether the new instrument is one with many 
possibilities, and it will appeal to people with widely 
different interests. G: Vi. ‘Boxs; 
A NEW INCANDESCENT ELECTRIC 
LAMP. 
NEW incandescent electric lamp with an 
efficiency of about o-5 watt per candle-power has 
just been placed on the market by several of the 
leading manufacturers in this country. It is only a 
few years since the tungsten filament lamp, with an 
efficiency of between 1 and 13 watts per candle-power 
appeared, to displace the carbon filament lamp the 
efficiency of which was between 3 and 4 watts per 
candle-power. In the case of the “ half-watt'’ lamp, 
however, there is no change in the material of the 
filament. This is still tungsten. 
Hitherto the tungsten lamp has been run at a tem- 
perature of about 2100° C., for although this is 
roughly-800° C. below the melting point of the metal, 
an effort to obtain a higher efficiency by employing 
a higher working temperature produced a deposit of 
metallic tungsten on the bulb. Analysis of the residual 
gases left in the bulb after exhaustion showed that the 
only one which could cause this effect was water 
