Improvements in Apparatus for Measuring and Indicating the Deflection of Substances under Pressure or Strain.
Year: 1896

page_text: Date of Application, 16th Dec., 1896
Complete Specification 1 eft 3rd Aug 1807 Accented 2nd Oct.
1207
[Communicated from abroad by ALESSANDRO MEIANI of Spezia in the Kingdom
of Italy Gentleman.]
Improvements in Apparatus for Measuring and Indicating the
Deflection of Substances under Pressure or Strain.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 322, High Holborn, in the County of Middlesex, 6, Lord Street,
Liverpool, and 6, Bank Street, Manchester, both in the County of Lancaster,
and Lower Temple Street, Birmingham, in the County of Warwick, Civil
Engineer, do hereby declare the nature of this invention to be as follows:-
The present invention relates to a micrometric apparatus for measuring the
deformation of engines, boilers, or other apparatus subject to deformation under
a given pressure.
In the centre of a cylindrical box is fixed a pinion the axle of which is supported
by a piece bearing at its upper end a pointer which can traverse the whole cir-
cumference of a dial covered by a glass plate in order to protect it from dust and
moisture.
The said pinion engages in a toothed rack which can oscillate upon its pivot.
The box bears at its diametrically opposite ends two appendices. In the first
of these is a piece with an arm more or less long, which can be screwed, whereas
in the other there can be inserted in a cylindrical sleeve a bar bearing at one of
its ends a little link connected to a lever and at the other screw threaded end a
nut. Between this latter and the head of the appendix is interposed a spiral
spring formed of a steel wire the use of which is hereinafter described. At the
threaded end aforesaiu is screwed another bar bearing a rider upon which may be
fastened or screwed an end or arm. By screwing or unscrewing the rider which
is provided at each end with a screw threaded in a contrary direction the one to
the other, the end may be drawn nearer or pushed further away. When the
instrument is placed in tension any movement of the rider is prevented by
screwing up hand screws to the point or arm of the bar. Any movement of the
bar will be transmitted to the rack by means of the link of the lever and of the
second link in relation to the distance from the point of application to the end of
the lever from the centre of oscillation. The rack may describe arcs of a certain
number of degrees more or less in relation to those described by the ends of the
link according as the point is more or less removed from the centre and the arcs
described by the pointer in relation to those described by the rack will be pro-
portionate to the difference of the radius of this latter to the radius of the pinion.
In consequence of this every movement however small it may be of the bar can
be indicated by the pointer upon the dial by a sufficiently large arc. In order to
prevent the bar from following the rider in its motion of rotation, there is placed
a screw upon the appendix the end of which can engage in a groove in the bar
itself, but not turn.

page_text: The method of operation of the apparatus is as follows:-
The pointer in its normal position is at Zero on the dial, and the spring is
slightly stretched. Supposing that it be required to measure the deformation which
the plates of a boiler may experience: the points are arranged of a suitable length
and the places selected upon which the points of the apparatus are to be applied.
The apparatus being prepared, the rider is compressed that is to say, the spring
is stretched, the ends of the points being able to move apart in order to be held
between the two boiler plates; consequently the bar will be obliged to rise in the
sleeve and to transmit thereby motion to the pointer by means of the mechanism.
In this manner the needle is caused to pass over the interval of the dial between 10
and Zero and is then stopped at Zero. The apparatus is now in position to com-
mence work. It is evident that if the water in the boiler be subjected to pressure,
and if the plates experience the least deformation this deformation is felt by the
ends of the points which will approach each other if the deformation is positive,
or will move apart in consequence of the spring if the deformation is negative,
and will transmit their movement to the pointer which motion can be perceived
by the dial even to a fraction of a millimetre according to the deformation suffered
by the plates. Having attained the fixed limit of pressure, and supposing the
plates have suffered deformation by gradually reducing the pressure it may be
seen whether the deformation is permanent, or if the plates tend to reassume their
first shape and at what pressure the deformation becomes permanent.
This apparatus can, as may easily be perceived, measure in the same manner
deformations of any engines or apparatus, work, or the like, which is liable to
strains which tend to deform it, as for instance, cranes, bridges, caissons, and the
like.
Improvements in Apparatus for Measuring and Indicating the
Deflection of Substances under Pressure or Strain.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 322, High Holborn, in the County of Middlesex, 6, Lord Street,
Liverpool, and 6, Bank Street, Manchester, both in the County of Lancaster,
and Lower Temple Street, Birmingham, in the County of Warwick, Civil
Engineer, do hereby declare the nature of this invention and in what manner the
same is to be performed to be particularly described and ascertained in and by
the following statements:-
The present invention relates to a micrometer or apparatus for measuring the
deformation of engines, boilers, or other apparatus subject to deformation under
a given pressure.
Referring to the accompanying drawings
Figure 1 represents a vertical section of the apparatus.
Figure 2 shews a horizontal plan.
Figure 3 is a horizontal view of the dial placed upon the box, with the pointer.
Figure 4 is a horizontal view of an arm of the lever which can be engaged with
another arm, and be held in position by a set screw r.
In the centre of a cylindrical box A. is fixed a pinion B the axle of which is.

page_text: supported by the piece C (Figure 2) bearing at its upper end a pointer I which
can traverse the whole circumference of the dial Q (Figure 3), covered by a glass
plate in order to protect it from dust and moisture.
The pinion B engages in a toothed rack S which can oscillate upon its pivot P.
The box A (Figures 1 and 2) bears at its diametrically opposite ends two
appendices R V (Figures 1 and 2). In the first of these is a piece with an arm L
more or less long, which can be screwed, whereas in the other it can be inserted
in a cylindrical sleeve a bar G bearing at one of its ends a little link G' connected
to the lever M and at the other screw threaded end gl a ring D. Between this
latter and the head of the appendix V is interposed a spiral spring formed of a
steel wire K, the use of which is hereinafter described. At the threaded end g¹
is screwed another bar bearing a rider X upon which may be fastened or screwed
the end or arm h. By screwing or unscrewing the rider X which is provided
at each end with a screw threaded in a contrary direction the one to the other
the end (Figure 2) may be drawn nearer or pushed further away. When the
instrument is placed in tension any movement of the rider is prevented by
screwing up the milled nuts a b against the ends of the rider X. It is evident on
inspection of the drawings that any movement of the bar G will be transmitted to
the rack S by means of the link G', of the double lever M', and of the second
link M in proportion as the distance from the fulcrum or pivot s to the end g of
the lever M is to that of the rack S from the centre of oscillation P. It will be
obvious that the rack S may describe arcs of a certain number of degrees more or
less in relation to those described by the ends g of the link M according as the
points is more or less removed from the centre l' and that the size of the arcs
described by the pointer in relation to those described by the rack will be..
determined by the difference betweeen the distance between the teeth of the rack
& the point P, and radius of the pinion B. In consequence of this every move-
ment however small it may be of the bar can be indicated by the pointer upon
the dial by a sufficiently large arc. In order to prevent the bar G from following
in its motion of rotation the rider X there is placed a screw 'T' upon the appendix V
(Figure 1) the end of which can engage in a groove in the bar itself, but not turn.
The method of operation of the apparatus is as follows:-
As may easily be seen from the drawings the pointer in its normal position is
at Zero on the dial, and the spring K is slightly stretched. Supposing that it
be required to measure the deformation which the plates of a boiler may
experience; the points are selected of a suitable length 'use being made if need
be of the prolongation represented by Figure 4 in case one of the arms should
be too short, and the points are fixed upon which its ends are to be applied. The
apparatus being prepared the rider is compressed that is to say, to stretch the
spring, the ends of the point being able to move apart in order to be held between
the two boiler plates, it will follow that the bar G will be obliged to rise in the
sleeve V and to transmit thereby motion to the pointer. I by means of the
lever M M, of the rack S, and of the pinion B. In this manner the needle is
caused to pass over the interval of the dial between 10 and Zero and is then
stopped at Zero. The apparatus is now in position to commence work. It is
evident that if the water in the boiler be subjected to pressure, and if the plates
experience the least deformation this deformation is felt by the ends of the points
which will approach each other if the deformation is positive, or will move apart
in consequence of the spring K if the deformation is negative,and will transmit
their movement to the pointer I which motion can be perceived by the dial even
to a fraction of a millimetre according to the deformation suffered by the plates.
Having attained the fixed limit of pressure, and supposing the plates have
suffered deformation by gradually reducing the pressure it may be seen whether
the deformation is permanent, or if the plates tend to reassume their first shape
and at what pressure the deformation becomes permanent.
This apparatus can, as may easily be perceived, measure in the same manner
deformations of any engines or apparatus, work, or the like, which is liable to

page_text: strains which tend to deform it, as for instance, cranes, bridges, caissons, and the
like.
In the drawings the dial is divided into tenths of millimetres, but it might
well be divided into fiftieths, and the range of the pointer might also be augmented
or diminished.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed as communicated to me
by my foreign correspondent, I declare that what I claim is:-
1. A micrometric apparatus devised to measure the deformation of the plates
of steam boilers or other apparatus susceptible of deformation characterized by
having a cylindrical box enclosing a system of levers, actuating a rack which
engages with a pinion keyed upon a central shaft provided at its upper end with
a pointer adjusted to a communicating dial, the apparatus having, moreover, two
appendices one opposite the other, in one of which bars may be screwed of
different lengths and in the other of which slides a bar connected by means of a
rider to another bar, substantially as hereinbefore described afd shewn in the
drawings.
2. In the micrometric apparatus claimed in Claim 1 the arrangement of the
bar G sliding in an appendix or sleeve V being held in this normal position by a
spring and having a screwed end upon which is screwed a rider bearing at the
opposite extremity a point or arm in such a manner that by turning the rider in
one direction the point h approaches the box whilst if the rider be turned in the
opposite direction it moves away from the box, substantially as hereinbefore
described and shewn in the drawings.
Dated this 3rd day of August 1897.
W. P. THOMPSON & Co.,
Of London, Liverpool, Manchester and Birmingham,
Patent Agents for the Applicant.