4 ) 
308 
lished as a supplement to the bulletin. The Preolenna 
Coalfield (Bulletin 13, 1913) contains Permo-Carbon- 
iferous seams amounting in the aggregate to 6 ft. 
6 in., situated under the Campbell Range some fifteen 
miles south-west of the north coast at Wynyard. 
Prospecting by diamond-bores is advised. No coal is 
to be expected near Wynyard (p. 71). 
The Geologicat Survey Branch of the Department 
of Mines of New Zealand continues its handsome 
series of quarto publications. Petrographers may be 
disappointed with Bulletin No. 12, ‘‘The Geology of 
the Dun Mountain Subdivision,” since the exception- 
ally fresh olivine-rocks of Dun Mountain have made 
the district famous for half a century. The biblio- 
graphy on pp. 6-8 perhaps explains why little more 
need be written on their nature and alliances. The 
authors, J. M. Bell, E. Clarke, and P. Marshall, 
describe a new rock-species, Rodingite, on p. 31. This 
consists of grossularite and diallage, the percentage 
of silica being 40, of lime 31, and the specific gravity 
being as high as 3-4. The authors do not see their 
way towards explaining this rock either by absorption 
of the Maitai limestone or by differentiation in the 
ultrabasic mass. The main object of the present 
bulletin has been a review of the prospects of the 
associated copper ores. The mineral from which the 
more superficial ores are derived (p. 44) is a cupri- 
ferous pyrrhotine, containing traces of gold, silver, 
cobalt, and nickel. This is interestingly associated 
with serpentinised peridotites. The chromite in the 
peridotites has not been mined since 1865. Dun 
Mountain, a rounded mass supporting little vegeta- 
tion, is figured on plate iv. 
Bulletin No. 13, by P. G. Morgan, who is now 
director of the Survey, describes the Greymouth sub- 
division of North Westland, where coal-seams occur, 
conformably overlain by marine Eocene strata. The 
Pleistocene glacial gravels are worked for gold, and 
there is said to be a probability that the Kotuku oil- 
field will prove profitable on further exploration. The 
petroleum occurs in various Cainozoic rocks above the 
local Coal-Measure series, and its source is at present 
unknown. 
Bulletin 14, by E. Clarke, is also concerned mainly 
with petroleum, in the New Plymouth subdivision of 
the Taranaki division, on the jutting promontory of 
the west coast of the North Island. The iron-sands 
that compose the Recent sand-dunes and beaches are 
also considered, owing to their well-known richness 
in magnetite and ilmenite. Bulletin 15, by J. M. Bell 
and C. Fraser, takes us to the Hauraki division of 
the North Island, where the town of Waihi, pictur- 
esquely situated, and illustrated in a folding plate, is 
the active centre of gold and silver mining. The ore 
is electrum for the most part, and the veins occur 
in altered Cainozoic andesites or dacites resembling 
the propylites of Hungary. Deposition is believed 
to have taken place from hot solutions, which brought 
up silica also, and to have been promoted by a fall 
of temperature near the surface (p. 179). Siliceous 
geyser-deposits occur in the middle of the volcanic 
series, and cinnabar has been found in them at 
Mackaytown (p. 59). The physiography of the rugged 
country is well described, and its irregular structure is 
attributed to the occurrence of epochs of denudation 
between those of volcanic deposition (p. 27). 
R. Speight, L. Cockayne, and R. M. Laing have 
made an interesting study of the Mount Arrowsmith 
district, on the eastern slope of the Southern Alps in 
Canterbury (Trans. New Zealand ‘Institute, vol. xliii., 
Pp. 315), in which the physiography described by the 
firstnamed author is used by his colleagues as a 
basis for a report on plant-distribution. The paper, 
with its details of glacial sculpturing and deposition, 
NO. 2325, VOL. 93] 
NATORE 
J 
[May 21, 1914 
is a good example of modern geographical inquiry into 
the origin of surface-forms. The rivers of Canterbury 
are held (p. 320) to radiate from a lost highland to the 
west, which has been cut away by denudation, and 
formed the higher part of the peneplain on which they 
originally flowed. Gr. Ac Ay Mee 
THE DEVELOPMENT AND PROPERTIES 
OF THE COTTON FIBRE. 
HE standard accounts of the cotton fibre are 
curiously inaccurate. Mr. W. Scott Taggart has 
directed attention to some of the more glaring errors 
in his ‘‘Cotton Spinning” (vol. i., 1896; London: 
Macmillan and Co., Ltd.), as did also the present 
writer independently in 1905 (Khedivial Agricultural 
Society’s Yearbook, 1905), when the cytology of the 
fibre was traced up to a week after the opening of the 
flower. Some additions to this account were outlined 
in my ‘Cotton Plant in Egypt”? (London: Macmillan 
and Co., Ltd., 1912), and a serious attempt was then 
made to ascertain how and when environmental 
effects operated on the properties of the fibre during 
maturation, and also to elucidate the real nature of 
the infinitesimal differences which the ‘sixth sense ”’ 
of the expert classifier of lint cotton can perceive. 
(1) By pickling a complete series of bolls from 
flowering to maturation in 1912 we showed definitely 
that the first half of the maturation period is occupied 
in the lengthening of the lint, and in the enlargement 
of the capsule and seed. Thickening processes take 
place in the second half of the maturation period. 
Thus a fibre may be short, but subsequently thicken 
satisfactorily, or conversely. Bad weather or soil in 
the latter half of maturation may weaken the fibres, 
but cannot affect the “‘ predetermined ’’ length. 
(2) A number of open flowers in a wide-sown pure 
strain were marked every day for sixty days in 1912 
and allowed to ripen normally. Each sample was 
then combed, measured, and ginned, weighed to deter- 
mine various constants, tested for breaking strain of 
the fibre on an automatic invention, and graded for 
strength; the results were examined statistically and 
graphically. They confirmed the developmental 
evidence; on shifting the breaking-strain curve back- 
wards over thirty days’ displacement, it was found to 
be substantially identical with the lint-length curve. 
The cause of fluctuation in ginning-out-turn (ratio 
of lint to seed-cotton) has long been a puzzle. With 
this material it was traced provisionally to fluctuation 
in the number of lint-hairs which sprout from the 
seed-coat ; its determination is therefore effected when 
the flower is about to open, which was, a priori, the 
least likely time. 
Plotting breaking-strains against ‘“‘strength”’ as 
determined in hand-pulling by an expert (Mr. H. C. 
Thomas, of Alexandria), the two were found to be 
completely independent; the expert unconsciously 
integrates breaking-strain with sectional area; samples 
of the same pure strain with respective breaking- 
strains of 12 grams and 2 grams were both graded as 
“SS” in a scale of seven grades. This leads on to 
a new definition of ‘‘fineness’’ in cotton fibre; it is 
not due primarily to differences in fibre-diameter, but 
to differences in the thickness of the lint cell-wall. 
‘*Weakness’’ of a sample is thus mainly irregularity 
in breaking-strain. a 
Determinations of fibre-weight with a micro-balance 
showed incidentally that an ordinary seed of Egyptian 
cotton bears about 10,000 fibres, and that weight is 
closely related to breaking-strain. The spinning into 
yarn introduces fresh complications, with which we 
have not dealt. 
It should be obvious to those familiar with the sub- 
