218 
NATURE 
[APRIL 30, 1914 
the path of the beam a glass plate or prism which 
transmits part and reflects part, as shown in Fig. 2 
(the Powell and Lealand type) where 1 repre- 
sents the glass plate, and 2 is a reflecting prism. 
In this form resolution is unimpaired, but the 
instrument is bulky, and there may be a good deal 
of difference in the amount of light which reaches 
the two eyes. 
A great advance has recently been made in the 
last-named form by Messrs. Beck, in this country, 
and Messrs. Leitz, in Germany, by the use of a 
half-silvered film cemented between two prisms. 
The silvered film is semi-transparent and allows 
part of the light to pass through and part to be 
reflected by the surface of the prism into the 
second tube. 
Fig. 3 repre- 
sents the con- 
struction in 
the Beck 
model, | where 
EA represents 
tite silvered 
film between 
thee t wo 
prisms. 
In both the 
Beck and_ the 
Leitz model, 
resolution is 
unimpaired, the 
illumination 
in, both e¢ye- 
pieces is the 
Sea me; the 
instrument is 
much less 
bulky than 
yhr e o. Lee 
forms, and 
short tube- 
lengths can be 
retained. 
There can be no doubt of the superiority of this 
binocular form over the ordinary monocular 
microscope. Eye-strain is lessened, and there is 
an increased ‘‘vividity’’ about the image, even 
though a true stereoscopic effect is not attained. 
It is particularly valuable in the examination of 
objects with dark-ground illumination; more 
seems to be visible than with the ordinary mono- 
cular microscope. 
There is an important difference between the 
Beck and Leitz models in the adjustment of the 
distance between the two eye-pieces to compensate 
for the varying distance between the two eyes in 
different individuals. In the Leitz model (Fig. 4) 
the tubes carrying the eye-pieces are parallel, in 
the Beck model they diverge (see Fig. 3). The 
inter-ocular distance in the former is adjusted by 
an arrangement which alters the distance between 
the two tubes; in the latter the inter-ocular distance 
is varied by lengthening or shortening the diverg- 
ing tubes. Now the former method entails much 
less alteration of tube length than the latter, and 
NO. (2322 Vion .@2)| 
Fic. 4.—The Leitz binocular microscope. 
inasmuch as the best lenses are corrected for a 
particular tube-length, for critical work we cannot 
help thinking that the Leitz adjustment is de- 
cidedly superior to that which obtains in the Beck 
model. ! R. T. HEWLETT. 
THE SCOTTISH ANTARCTIC EXPEDITION: 
RITISH men of science will notice with keen 
regret the unpromising answer given by the 
Government to the application for 3,800]. to com- 
plete the publications of the Scientific Reports of 
the Scottish National Antarctic Expedition of 
1g02—1904. The application has been supported 
by a very influential body of Scottish scientific 
opinion. The expedition was entirely equipped 
by money privately raised in Scotland, and was 
mostly due to the generosity of Messrs. J. and A. 
Coats. The discovery by the Scotia of Coats 
Land is generally recognised as the most impor- 
tant addition to our knowledge of the boundaries 
of the Antarctic continent that has been made by 
the Antarctic expeditions of this century. It 
added half a million square miles to the previous 
estimates of the area of the continent and settled 
the position of the coast in the one part where 
there was no clue to its situation. 
The Scotia made a series of voyages in the 
least known of the Antarctic seas and, as the 
whole of the energies of the expedition were de- 
voted to scientific work, it made collections and 
oceanographic observations of the highest impor- 
tance. Five volumes of its scientific results have 
been published and three others have been arranged 
owing to a grant previously made by the Govern- 
ment. Four further volumes are required to 
complete the series. The remaining volumes 
would be mainly devoted to description of the 
biological collections, and the memoirs have been 
already prepared by many distinguished British 
and foreign naturalists. The work of these men of 
science has been entirely gratuitous and it is pecu- 
liarly ungracious to the foreign contributors that it 
should be wasted owing to the lack of the compara- 
tively small sum required to complete the publica- 
tion. 17,5001. has been set apart to defray the cost 
of preparing the reports on the scientific work of the 
Terra Nova expedition, which excludes the reports 
on natural history which are being published at 
Government expense by the British Museum; 
hence the expenditure on the Scotia publications 
has not been excessive. Much confusion in bio- 
logical nomenclature may be produced if the 
publication of these reports be delayed, so that 
they appear simultaneously with those prepared 
from the collections of later expeditions. 
The application to the Treasury for a grant for 
the publication -of the results has received very 
influential support; it is accompanied by letters 
from all the leading scientific societies and author- 
ities in Scotland, and by the past and present 
1 In the preparation of this summary, free use has been made of the 
articles by Dr. Jentzsch and Mr. Conrad Beck in the Journal of the Royal 
Microscopical Society, 1914, part 1, pp. 1 and 17, For the loan of the blocks 
from which the illustrations are reproduced, we are indebted to Messrs. R- 
and J. Beck and Messrs. E. Leitz. 
