The Stourbridge Observer, Cradley Heath, Halesowen & District Chronicle.
Stourbridge, West Midlands, England, 1875-06-12 00:00:00

'WHITWORTH PLANES, STANDARD
MEASURES, and GI.INV

An interesting and suggestive lecture was given at
the Royal Institution, in London, on Friday evening
in last week, by Dr. Tyndall, who selected for his
subject "Whitworth Planes, Standard Measures, and
Gum"

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The lecturer fi.iit g a btief sketch 9f the career
of that most eminent mechanician Bir Joseph Whit-
worth, who from the first had kept one object
steadily in view in the manufacture of machinery
and tools, and that object being mechanical veracity.
He has always been celebrated for perfect accuracy
in his engineering tools, which have earned for him
a justly Merited renovni throughout the world.
Sir Joseph's starting point had been to obtain a true
plane which should serve as a datum line, so to
speak, by which all untruthful work could be
detected, the extent of its error estimated, and the
fault corrected. This true plane was not obtained
Without much thoughtful work, the process being
explained by Dr. Tyndall. Briefly it consisted in
coating the surface of one plane 'with colouring matter
and by placing another plahe upon it the excrescences
were detected. After the planes had been made per-
fectly true, if placed one on the other and pressed by
the hand they would adhere. According to Sir
Joseph's theory, the air was entirely displaced from
between the metallic surfaces of the planes, and the
two masses of metal were retained in contact by reason
of the pressure of the external atmosphere. Dr. Tyn-
dall stated that he had doubted that theory, and rather
attributed the cohesion to molecular attraction. In
order to test the correctness of his views, he had placed
a pair of Whitworth planes in contact under the air
pump, and, after obtaining a perfect vacuum, the plates
still remained in contact. This experiment the lecturer
repeated before the audience. A pair of planes in
centatt; each weighing 31b., were suspended in a
vacuum which was shown to be nerly perfect. To
the bottom of the lower plane 121 b. of lead was
attached, giving a total weight of 151 b. suspended from
the upper plane simply by molecular attraction arising
from mechanical truth. Dr. Tyndall next proceeded
to point out the practical application of the Whitworth
planes, which was the production of the perfect
measuring instruments known as Whitworth gauges,
and which in their turn were the means of enabling
perfectly accurate machinery to be constructed. The
lecturer explained to his audience the construction of
two measuring machines, one of which measured to
and recorded the ten thousandth part of an inch,
while the other was equally effectual in ascertaining
the difference of the one millionth part of an inch.
Some idea of what the one-millionth part of an inch
means may be gathered from the fact that 4,000 of
these parts only equal the thickness of a sheet of ordi-
nary French writing paper. Dr. Tyndall then pro-
ceeded to describe the Whitworth rifle with its hexa-
gonal bore and hardened bullet, and with which such
sPlendid results cif range, aectixaey, and penetration
had been obtained. He pointed out the superiority of
the modern elongated projectiles over the old spherical
bullet and shot, and explained the reasons for the ad-
vantages gained. He then described Sir Joseph's sys-
tem of polygonal rifling for heavy guns, and illustrated
the results of the system as applied to light artillery
by some reiearkaole exaMpleft of ircn penetrated
in some cases partially and in others wholly
by Whitworth shot. The lecturer then entered
upon a consideration of the relative values of
flat-headed and pointed projectiles, observing that Sir
Joseph had done sufficient to render it important that
this question should form the subject of a thorough
and searching investigation at the hands of those
who wete competent to deal with it. The remark-
able qualities of Whitworth metal next etgaged at-
tention and Dr. Tyndall explained its manufacture,
which 'he had recently witnessed at Sir Joseph's
works at Manchester. He stated that the metal
was simply steel compressed while in the fluid con
dition. This compression was effected by submitting
the steel immediately upon its being run into the ingot
mould to the potion of a powerful hydraulic press.
All the aso were forcibly expelled, all mechani-
cal cavities perfectly closed, and a thoroughly homo-
geneous and sound metal produced. The tests to
which this metal had been submitted were then given,
and showed its remarkable tenacity. Cylinders had
been burst by the explosion of frequent confined charges
of gunpowder, but they had simply been torn open and
not broken into'fragments as cylinders of other metals
would have been. Cylinders having ends closed by
strewed plugs were shown, in Which some 50 charges of
powder had been fired, with but little effect as regatds
distortion, although but a small touch-hole was avail-
able for the gases generated by the explosion. The
lecturer concluded an interesting discourse by paying a
tribute to the talent and genius of Sir Joseph Whit-
worth.