September, 1954] K. N. RAMCHANDRAN AND P. R. YERI 155
jector with the embedding medium facing the objective and the diameter measure-
ments recorded as outlined above, at the major and minor axis of each fibre. The
mean is expressed in microns with a tolerance limit of two microns.
LENGTH MEASUREMENT
Length of wool fibres contributes towards the spinning property, as the longer
fibres allow greater draft during spinning. The wool of the sheep in India contains
in general an outer-coat of coarse fibres and fine under-coat. The coat is not homo-
geneous and hence the sampling for fibre length measurements should take into
consideration the dual coatedness of the fleece.
(i) Sampling from a sheep. A sample from an area of 3 in. x 3 in. from each
of the six regions of neck, wither, shoulder, side, back and britch is cut. Each
sample is spread lockwise without disturbing the natural lock formation and spread
on a black velvet board so as to arrange the basal portion against a steel rule. Three
bunches of approximately 100 fibres are drawn at random and this constitutes the
sample for length measurements.
(ii) Sampling from a bale of wool. Eight pickings of approximately 2 oz.
each are drawn at random from the different portions of the bale. These samples
are thoroughly mixed lockwise and successively halved, so that the final sample is
about 2 oz. At each stage, of halving, one part is discarded at random. The locks
of these samples are superimposed over one another and spread over a length of
six inches on a black velvet board. The arrangement is set against a steel rule
and six random drawings of approximately 50 fibres constitute the final sample.
Procedure
The sample is washed free of grease and dirt in a two per cent solution of neutral
soap and rinsed in two changes of distilled water. After drying, each fibre in the
sample is straightened by holding two extreme points of the fibre with two pairs
of forceps against a steel rule on a black velvet board. The length measurements
are recorded in groups of equal intervals of 0.5 cm. length.
Length measurement apparatus
An instrument (Plate VII, Fig. 1) for the rapid determination of the length has
been evolved by the Wool Industries Research Association. It is considered that
the instrument will enable quick recording of fibre length in the form of frequency
distributions. In a laboratory where a considerable number of samples will have
to be tested it is felt that an apparatus of this type will be useful. A detailed
description of the instrument is given below :
The machine comprises two elements, the measuring unit proper and an auxiliary
counter. The counter is not an essential part of the machine but is of great con-
venience in use.
The method of operation is as follows :
A lead screw extends the whole length of the front of the machine. This is
clearly shown on the photograph. It normally rotates at a slow speed, being driven
by the motor visible at the far end of the machine. Fibres are drawn singly from
the samples to be analysed, employing a special pair of forceps supplied with the
machine. These may be seen retained in a clip just in front of the motor. The
fibre is gripped at its end by the forceps, the points of which are engaged in the