AN IMPROVED APPARATUS OR MACHINE FOR TESTING AND REGISTERING OR RECORDING THE STRENGTH, ELASTICITY, AND DUCTILITY OF WOOD, IRON, AND OTHER MATERIALS
Year: 1874

page_text: LETTERS PATENT to George Haseltine, of the "International Patent
Office," Southampton Buildings, London, Doctor of Laws, for the
Invention of "AN IMPROVED APPARATUS OR MACHINE FOR TESTING AND
REGISTERING OR RECORDING THE STRENGTH, ELASTICITY, AND DUCTILITY OF
WOOD, IRON, AND OTHER MATERIALS."-A communication from abroad
by Robert Henry Thurston, of Hoboken, New Jersey, United States
of America.
COMPLETE SPECIFICATION filed by the said George Haseltine at the
Office of the Commissioners of Patents, with his Petition and
Declaration, on the 7th January 1874, pursuant to the 9th Section
of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
HASELTINE, of the "International Patent Office," Southampton Build-
ings, London, Doctor of Laws, send greeting.

page_text: "
STRENGTH, ELASTICITY, AND DUCTILITY OF WOOD, IRON, AND OTHER MATERIALS,'
and have petitioned Her Majesty to grant unto me, my executors,
administrators, and assigns, Her Royal Letters Patent for the same, and
have made solemn Declaration that it has been communicated to me
from abroad by Robert Henry Thurston, of Hoboken, New Jersey,
United States of America.
NOW KNOW YE, that I, the said George Haseltine, do hereby declare
that the following Complete Specification, under my hand and seal,
fully describes and ascertains the nature of the said Invention, and
in what manner the same is to be performed, in and by the following
statement, reference being had to the accompanying Drawing forming
a part of this Specification
This Invention is embodied in an apparatus in which the strain to be
applied to test the strength or elasticity of any material is transmitted
through the piece to be tested- by two-independent opposing forces, one
of which in combination with a stationary guide gives a movement to a
pencil holder and pencil, and the other gives a movement to a table
covered with a paper similar to that used in taking indicator diagrams
from a steam engine, whereby in the performance of the test of the
material the differential movement between the paper and the recording
pencil induced by the yielding of the fibres of the piece which is being
tested to the strain applied to it shall express the quantities of strength,
clasticity, or ductility which the material tested possesses.
"

page_text: work.
The framework A, A', supports two arms B and C, which are suspended
from and swing about independent axes in the same line. The arm B
carries a weight D, and the arm C a handle E by which it is moved. To
the frame is attached a guide curve F which approximates to a segment
of a cylinder, cut by a plane diagonal to the plane of revolution of the
cylinder. Against the edge of this guide a spring pencil holder I bears;
and this holder and its pencil are as the weighted arm B is vibrated
moved by means of the guide F across the curved surface of a table G
which is attached to the end of the arm C. Upon the cylindrical face of
the table G a sheet of paper is placed, upon which the pencil held by the
spring holder will trace a line.
•
The method of experimenting with torsional strains will be first
explained. The axes of the arms B, C, are counterparts of each other,
and are designed as shown in Figure 2, each having rectangular
recesses L, L', to receive the ends of the pieces to be tested, which are
shown on a larger scale in Figures 3 and 4. The material is accurately
fitted to its place, one end filling the recess in the axis of the weighted
arm B, and the other fitted to the corresponding recess in the axis of the
arm C. The normal position of the arm B is vertical, but when a force
is applied to the lever C it is transmitted through the test piece to that
arm, causing it to swing outward, the effect being to react upon the test
piece with a force proportioned to its moment. While the weight of the
arm is a constant quantity, the leverage with which it acts is not
uniformly progressive in amount, so equal angular movements through
different parts of the arc traversed by the arm B do not exert equal
moments of pressure. Therefore in order that all the ordinates of the
curve described by the pencil J should be measurable by a common
scale, it becomes necessary so to shape the guide curve F as to move
the pencil through equal spaces for equal increments of moment.
If a material absolutely without elasticity were placed in the apparatus
and force applied to move the arms C, the relative positions of the arms B
and C would not change, and the line traced would be a vertical straight
line, but as a matter of fact all materials yield more or less under a
force applied, and as a consequence of such yielding the arm B will have
an angular movement less than that of the arm C, and the amount of

page_text: such angular deflection becomes a measure of the distortion of the
splainer tested.
Suppose it be determined to experiment on the torsional resistances of
white pine, the piece is turned in the middle to the exact diameter, say
seven-eighths of an inch; the record will be as shown in Figure 5, and
numbered 1, the blank for the diagram, if ruled, being made parallel
with the planes in which the arms move.
The horizontal and per-
pendicular lines passing through this point become bases from which
the respective ordinates and abscissas of the curve will be measured. If
the blank be not ruled until after the curve has been described, a line
drawn through the points of commencement and termination of the
curve will be the horizontal base, and a line at right angles to this
base drawn through the points of commencement will be the perpen-
dicular base.
When pressure is applied to the handle E it is opposed by the weighted
arm B, and with increasing amount as it swings outward, the pencil
attached to it being thrown forward by its contact with the guide
curve F to a corresponding degree until the stress becomes such as to
destroy the elasticity of the material; the weight then drops as the
fibres yield, the pencil retreating along its guide until it reaches the
position from which it started, when the arm is seen to be vertical, and
the material twisted apart.
On examining the registry which has been made it will be found that
as the stress increases, the yielding of the wood keeps the pencil from
following the diagram table with equal angular motion, so that the line
described inclines backward from the perpendicular, according to the
increased amount of twist given, and the angle of inclination which
it makes with the perpendicular exhibits the stiffness of the test piece.
When the angle of torsion has reached 25° the material has attained its
limit of elasticity, and measuring the corresponding ordinate of the
curve it is found to be subjected to a strain of eighteen foot pounds. A
slight additional twist parts the outer fibres, and then fibre after fibre
yields, the weighted arm dropping and the torsional angle increasing
until the material ceases to offer resistance, after twisting through an
angle of 135°.
A trial of Spanish mahogany would result as shown by curve 8.
Considerable strength and stiffness are shown by the height of the curve,

page_text: and its slight inclination from the perpendicular. With a pressure of
forty-six foot pounds its torsional angle is but 15°; its brittleness is
shown by the rapid descent of the curve from this point. At a tortional
angle of 48° it is seen to intersect the curve of white pine, showing its
tortional resistance at that angle to be the same as that of the latter.
White oak has always been remarkable for its extraordinary toughness,
which quality is clearly shown by the length of the maximum abscissa
of its curve (Number 9). Its elasticity is but little impaired at an
angle of 65, and after passing that point it yields very slowly; even
when twisted through an angle of 250° it offers a resistance of ten foot
pounds.
In the case of hickory (Number 10) the resistance increases with the
amount of tortion until a maximum is reached, the line then drops to a
point considerably below, and thence again rises and passes another
maximum, which is only reached after a tortion of 75°; the resisting
moment then becomes considerably greater than at the limit of
elasticity.
By close observation of the test piece while yielding under stress it
will be seen that the first maximum was passed at the instant when the
lateral cohesion of the fibres being overcome they slipped upon each
other, and the bundle of loose fibres steadily yielding the curve dropped
until the second maximum was reached. Here yielding again occurred
this time by the breaking of the fibres under a longitudinal strain, or
that component tortional stress which takes a direction parallel with that
of the fibres in their new positions.
It will be clearly seen from the above examples that from the
diagrams may be deduced every condition attending the distortion and
fracture of the piece tested. When drawn upon the same card the
several diagrams present to the eye at once the relative stiffness,
elasticity, and strength of the materials used, and the areas included
between their curves and the base line, and proportional to their
tortional resilience.
Although all the examples given are of woods, they are taken for
convenience merely, the apparatus revealing with equal precision and
clearness the peculiarities of fracture of metals or any other materials.
For heavy work where the use of the weight would be inconvenient a
substitute is offered by the spring balances R, R', Figure 8, one or both

page_text: of which may be used. "In place of the arm C I use a worm wheel T
and its gear whicel C', the latter being placed upon the axis. The guide
curve will then not be required, the recording pencil partaking of the
movement of the balance by its connections S, S, or their equivalents.
Since the particles exposed to shearing and test offer a resistance very
nearly corresponding to their tensile strength, the verticale scale of the
diagram is a scale of tensile strength, and the machine' is thus an
apparatus for testing tensile strength, as well as the stiffness, torsional
strength, elasticity, ductility, and resilience of materials. With the
machine here illustrated the scale is about 25,000 pounds per inch when
the weight at the end of the arm is 100 pounds, the arm being five feet
in length.
In measuring resistances to tensile strains the material may be used
in the form of wire. The ends are secured to the periphery of the two
wheels W, W', attached the one to the hub or axis of the arm C, and
the other to the axis of the arm B, the wire passing around a third
wheel M, which is adjustable vertically to the length to be tested. The
operation is precisely the same as has been explained in connection with
torsional experiments, and the line described by the recording pencil
forms a diagram measurable by scale in like manner. The distance of
any point in the curve from the perpendicular base is a measure of
ductility, and is proportional to the stretch of the wire by a strain whose
amount is denoted by the height of the given point above the horizontal
base.
If the said apparatus is to be used for investigations of transverse
.strains, a bar of proper size is held at one end by a socket N fitted into
the recess of the hub of the arm B, and at the other end by the socket P
which is secured to the other arm C. The latter socket can be adjusted
in position according to the length of the bar operated upon. Pressure
is applied and a curve described as before, the ordinates of the curve
measuring the stress applied, and the abscissas exhibiting the corre-
sponding flexure.
It will be seen that the recording apparatus which forms a part of this
Invention may be applied by attaching proper multiplying levers to the
ordinary forms of machines for testing strength of materials.
Having thus fully described the said Invention, as communicated to
me by my foreign correspondent, and the manner of performing the
3

page_text: same, I wish it understood that I claim, an apparatus or machine
consisting of the weighted lever B and hand lever C, or the equivalents
thereof, arranged to operate in opposition to each other upon the
material to be tested, the said lever C giving a movement in one
direction to a table G covered with a paper, and the said lever B in
combination with a guide F giving a movement to a pencil holder and
pencil transversely to the plane of movement of the table, substantially
as herein-before described, whereby a diagram is described and recorded,
the co-ordinates of whose curve are proportional, one to the force
producing distortion or rupture of the material tested, and the other
to the degree of such distortion, and the area of the diagram is the
measure of the degree of resilience.
In witness whereof, I, the said George Haseltine, have hereunto
set my hand and seal, this Seventh day of January, in the
year of our Lord One thousand eight hundred and seventy-
Witness,
H. J. NOONE,
8, Southampton Buildings,
London.
GEORGE HASELTINE. (L.S.)