72 
NATURE 
Marci 21, 1912 
» 19 
The work of the aéronautics division has made 
govd progress; in particular the study of the best 
forms of aéroplane surfaces, and of the distribution of 
flow round such surfaces, has been greatly advanced. 
An opportunity of describing this work will arise later, 
on the issue of the annual report of the Advisory 
Committee for Aéronautics. 
The metallurgy department was occupied for some 
considerable time during the autumn with the trans- 
ference to the new Wernher building. The principal 
item of research work has been the investigation of 
the aluminium-zine alloys, carried out for the Alloys 
Research Committee of the Institution of Mechanical 
Engineers. 
Mr. Baker, the superintendent of the William 
Froude National Tank, has carried out a number of 
investigations, some of which have been already de- 
scribed in these pages. Careful comparisons have 
been made with Mr. Froude’s results at Haslar by 
tests on models to lines supplied by him, and experi- 
ments have also been carried out with a model similar 
to others tested at Clydebank and Washington. 
These tests have shown satisfactory agreement, and 
the national tank is now ready to go forward with 
general experimental investigations of ship resist- 
ances. 
In this short summary it is impossible to do more 
than touch on the many points of interest presented 
by the work of the laboratory. Enough, however, has 
been said to show that the laboratory continues fully 
to justify the appreciation which the great manu- 
facturing firms of the country have displayed of its 
value to industry. 
OZONE AND VENTILATION. 
pee Journal of the Society of Arts of February 9 | 
contains a paper by Messrs. Leonard Hill and 
Martin Flack on ‘‘The Influence of Ozone in Ventila- 
tion.’ ‘The authors. point out that whilst it is not 
legally permissible for the carbonic anhydride in the 
air of a factory to exceed a few parts per 1,000, no 
harm whatever is caused by breathing air containing 
up to 4 per cent. of this gas. A similar statement 
applies to deficiency of oxygen, which does not become 
important until the proportion falls to 14 or 15 per 
cent. These conclusions are quite in accord with the 
fact that, on account of the dead-space separating the 
lungs themselves from the open air about one-third of 
the air drawn into the lungs is re-breathed; it is thus 
quite impossible that a few parts per thousand of car- 
bonic anhydride in the outside air should affect the 
lungs, in which the percentage is normally about 
5 per cent. 
Another theory of the ill-effects of bad ventilation is 
the supposed liberation of organic poisons. This also 
is probably fictitious, as animals will live and thrive 
when supplied exclusively with air already breathed 
by other animals, and containing 33 per cent. of 
carbonic anhydride; they are liable to die of suffoca- 
tion if the air supply is interrupted, or if the per- 
centage of carbonic anhydride rises to 10 to 12 per 
cent. As an explanation of the discomfort arising 
from lack of ventilation the authors suggest: (1) the 
stagnation of the air, resulting in diminished evapora- 
tion from the skin, and a consequent sensation of 
lassitude; (2) the nausea caused by the odour emitted 
from an imperfectly washed crowd. The value of 
ozone in ventilation depends largely upon its power 
of removing this odour; sterilisation is perhaps less 
important as expired air is practically sterile; infection 
is conveyed by droplets of saliva, which cannot he 
removed bv ventilation, but soon settle, and may be 
removed when the room is dusted. 
NO. 2212, VOL. 89] 
| PP. 
LA HOUILLE BLANCHE.’ 
pee work of the French ‘‘ Direction de 1’Hydrau- 
lique"’ has already been the subject of two 
articles in these columns (May 7, 1908, and November 
25, 1909). On both occasions a tribute was paid to 
the very effective and thorough manner in which the 
department was carrying out its systematic investiga- 
tion into the hydraulic reserves of the mountain ranges 
of France. The volume now under review is the 
fourth of the series, and it sustains the favourable 
impression created by its predecessors. It brings the 
record of observations down to the end of 1910, com- 
pleting a period of very nearly eight years since the 
inception of the department. The service, in so far 
as it relates to the region of the Alps (which is the 
only range at present under observation, though the 
extension of the work to the Pyrenees is impending), 
is now concentrated under the direction of M. R. de la 
Brosse, whose former coadjutor, M. R. Tavernier, has 
become Inspecteur général de l’Hydraulique agricole. 
The area of country comprised within the purview 
of the inquiry amounts to 22,000 square miles, and 
lies immediately to the south of the Lake of Geneva, 
extending to the shores of the Mediterranean, and 
| being bounded on the east and west, respectively, by 
the Italian frontier and the river Rhone. The prin- 
cipal basins are those formed by the tributaries of 
the Rhone on its left bank between Geneva and the 
sea, the most noteworthy being the Isére, the 
Durance, the Var, the Arve, and the Dranse. Gaug: 
ing stations to the number of 180 have been estab- 
lished in suitable localities, and the total number of 
gaugings carried out to December 31, 1910, was 3116, 
of which 726 represent the work of the last twelve 
months. The greatest number of records taken at 
any one station amounted to fifty-nine, and the mean 
for the whole was seventeen. 
From the observations two factors, or coefficients, 
have been deduced. First the mean characteristic 
discharge, which represents the minimum guaranteed 
| for half the year; and, secondly, the modulus, or 
arithmetical mean of the discharges corresponding to 
the daily level. The former of these factors is valu- 
able in computing the industrial trustworthiness of 
a stream, and the second is an important element in 
connection with regularisation works. As an instance 
may be taken the case of the Durance at Rousset, 
where, during the five years 1905-9, the records show 
a variation in discharge between 18 and 440 cubic 
metres per second, giving as mean figures for the 
whole period a low-water discharge of 20 cubic metres 
| per second, a modulus of 68, and a total annual 
_ volume of 2,138,000,000 cubic metres. 
The mean 
characteristic discharge, i.e., the minimum on which 
| it is possible to reckon during half the time, is about 
46 cubic metres per second. 
The motive power in the French alpine region 
actually harnessed at the present time amounts to 
473,000 h.p., dvided approximately as follows :— 
Metallurgy, 210,000; power and light distribution, 
155,000; chemical products, 60,000; paper, cardboard, 
&c., factories, 30,000; electric traction, 10,000; mis- 
cellaneous, 8,000. Other schemes are now projected 
which will shortly raise the total to something in the 
neighbourhood of 2,000,000 h.p. 
The volume contains one or two useful essays by 
individual contributors on technical matters connected 
with the taking of observations, and there are several 
interesting photographs. Then follows part ii., which 
1 Service des Grandes Forces Hvdrauliques (Région des Alpes). Compte 
Rendu et Résultats des Etudes et Travaux au 31 Décembre, 19to- Tome iv., 
sc6. Annexe i., Cartes. pp. 14+8 cartes; Annexe ii.. Nivellements, 
23 planches. (Ministére de l’Agriculture, Direction de I'Hydraulique et des 
' Améliorations Agricoles, rort.) 
