464 
days, and the blood volume also slightly increases. 
On returning to lower levels the blood volume rises 
and the haemoglobin percentage decreases, but neither 
returns to its original level until several days later. 
Dr. H. E. Roaf found, when the weight of the 
kidneys is expressed by a similar formula, that n is 
approximately 1°5, and hence the body surface does 
not regulate the kidney weight. Possibly there is 
some reciprocal relation to the skin; or, like the blood 
volume of cold-blooded animals, the kidneys depend 
upon the mass of muscle in the body. 
In concluding this account of the section of physio- 
logy, we feel that some reference should be made to a 
new feature. The section was strengthened by 
having associated with it the first subsection of 
psychology. H. E. Roar. 
GEODETIC OBSERVATIONS AND THEIR 
VALUE. 
T is not always the greatest inventions, or those 
which come most prominently before the public, 
which effect the greatest revolutions in the field of 
practical science; it is often the perfecting of instru- 
ments that have been long in use which is chiefly 
responsible for progressive results of startling sig- 
nificance. For instance, in the scientific researches of 
chemical investigators, or in matters relating to 
pathology and meteorology, it is seldom that a fresh 
discovery is due to the invention of a new instrument; 
it is almost invariably the development of the power 
of assisting observation already existing in the old 
instruments which has effected new discoveries. This 
is peculiarly the case with modern instruments used 
in connection with geodetic work. It is the perfection 
with which the metal are can now be graduated with 
equal divisions representing degrees, minutes, and 
seconds which has so greatly altered the conditions 
under which geodetic triangulation can be extended. 
The improvements effected in base measuring appa- 
ratus is another factor in the rapid evolution of earth 
measurement and map-making all over the world; 
whilst the improved pendulum for the registration of 
the varying force of gravity, corresponding to the vary- 
ing conditions of density which obtain in the earth’s 
crust, renders investigations into the science of isostasy 
more simple and more certain than could possibly 
have been anticipated, say, fifty years ago. 
These developments in the processes of advancing 
the practice of geodetic measurement over the surface 
of the earth are of more importance than is generally 
recognised, because the direct connection between 
geodesy and geography is not rightly understood. 
Geodesy is not a mere abstract science dealing with 
the shape of the earth and solving mathematical 
problems connected with its eccentricity, or deter- 
mining the variable density of the earth’s crust by 
careful investigations into the force and direction of 
gravity; it furnishes the basis and the framework 
of all that extension of earth measurement of which 
the final outcome is the map. Geodesy offers but 
little field for such form of illustration as will readily 
fix it in the minds of men as a sound practical every- 
day working science essentially necessary for the 
economic and political advancement of civilisation. 
Geodesy began with the measurement of arcs on 
the earth’s surface in various parts of the world by 
the process of extending a series of triangles along 
that arc from a measured base at one end of it. 
Rigorous accuracy was the dominant feature of such 
measurements. The measurement of a base a mile 
1 Abstract of an address ¢elivered at the opening of the réoth session of 
the Royal Society of Arts on November 19, by the chairman of the council, 
Sir Thomas H. Holdich, K.C.M.G. 
NO. 2303, VOL. 92] 
NATURE 
[DeEcEMBER 18, 1913 
or so in length was effected formerly by means of 
“compensation bars”’ of a givem length, which were 
designed with infinite care and armed with mechanism 
for longitudinal, vertical, and transverse adjustment, 
and it was a most elaborate and lengthy process. 
The process was repeated at intervals, if the triangu- 
lation series was a long one, in order to ensure results 
as near absolute accuracy in linear measurement as 
was possible. It took months to measure a base. 
Now it is found that by using a wire composed of 
“compensating ’’ metals and stretched along a series 
of cradles or supports, the same result can be obtained 
in about one-tenth the time. The Jaderin apparatus, 
which includes a wire 25 metres in length, affords 
the simplest means of obtaining accurate base 
measurement; but there is still an appreciable defect, 
due to varying conditions of temperature, which 
renders it necessary to compare the wires before and 
after use with a standard measurement. The E6tvés 
torsion balance represents, perhaps, the latest improve- 
ment in apparatus for the measurement of base lines. 
Independently of the base, however, the real secret 
of the facility with which strictly scientific geodetic 
triangulation can be carried over large areas of new 
country lies in the improvement in the art of graduat- 
ing metal arcs, which has rendered the comparatively 
light and portable 12-in. theodolite equal for purposes 
of rigidly accurate observation to the old 2-ft. or 3-ft. 
instrument of the past. In India, where one of the 
first and most perfect systems of geodetic triangula- 
tion has been carried out, it used to be necessary 
to call quite a large number of carriers into the field 
to convey the clumsy old instruments from one 
observing point to the next. Paths had to be cut with 
much labour and patience through the jungle; roads 
had to be smoothed out and carried up the sides of 
the hills. The expense would have been prohibitive 
but that labour was cheap in those days. The time 
occupied over the process of completing observations, 
even at only one station, frequently lengthened out 
into months. Nowadays there is a new generation of 
scientific observers educated in English schools, who 
need lose no time in carrying first-class work through 
the wild tangle of African hills and forests to deter- 
mine a boundary; or in threading their way with 
infinite patience by the rock-bound defiles and snowy 
heights of the Himalayas to a junction with Russian 
| Surveys on the Pamins. 
It has always been the aspiration of English sur- 
veyors to link up the magnificent survey system of 
India with that of Russia. To a certain extent this 
was effected by methods which cannot be accepted as 
scientifically regular during the progress of the Pamir 
Boundary Commission in 1895. The surveyors did, 
however, actually close on a determined point common 
to both surveys (it was the first boundary pillar at the 
eastern end of Lake Victoria) after carrying’an irre- 
| gular triangulation across the great snowy ranges of 
the north-west, and the resulting agreement between — 
the two values was almost too good to be altogether 
satisfactory. The means did not justify the end. It 
was impossible to ascend the gigantic peaks of the 
intervening ranges within the limits of the time avail- 
able, and it was necessary, therefore, to be content 
with seeing across them here and there, under specially 
favourable conditions, instead of observing from them. 
Lately, however, a more regular and _ systematic 
attempt has been made to turn those ranges which 
cannot be crossed, and a direct series has actually 
| been driven round these gigantic buttresses of the 
north on to the Pamirs. The results of this extra- 
ordinary feat are not yet published, but they furnish 
an example of what may be attempted in these days 
by the introduction of an improved class of compara- 
\ tively small instruments. 
