IMPROVEMENTS TE PYDAWENERS
Year: 1875

page_text: Be
LETTERS PATENT to Robert James Wood, of the City of Glasgow, in
the County of Lanark, North Britain, Clockmaker, for the Invention
" IMPROVEMENTS TE PYDAWENERS ".
·PROVISIONAL SPECIFICATION left by the said Robert James Wood
at the Office of the Commissioners of Patents, with his Petition,
i on the 18th May 1875.
I, ROBERT JAMES WOOD, of the City of Glasgow, in the County of
Lanark, North Britain, Clockmaker, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN PYROMETERS," to be as
follows:-
: The nature of this said Invention or improvements in pyrometers
'consist, as regards the general construction of the instrument, of a dial
with graduated circular or segmental divisions and an indicating hand or
pointer on a spindle with pinion concentric to the divided dial, actuated
by a corresponding toothed sector or segment. By these improvements,

page_text: either fixed on the prime motion spindle or on a centre or stud carried on
a small double-armed bracket made to swivel round the index spindle, so
that it can be set and fixed to give more or less throw of the segment
and index over the dial to exactly suit the divisions in the first instance
by "trial and error," in shifting the axis of the sector laterally out of
line with the axis of the first motion spindle, which in this case is con-
nected by a short crank, with crank pin working up into the slot of a
short arm or crank fixed on the same axis as the toothed sector, so as to
actuate it, all which is contained within a glass cover of the usual hollow
brass or other protecting casing, having a new construction of short
hollow stem, with screw wheel on it, carried in a socket piece with
lateral screw spindle working in the screw wheel, and having a thumb-
screw outside for turning the case with gearing and dial round on the
axis of the first motion shaft to adjust or set the hand or pointer to the
zero point of the dial without turning the ordinary outer protecting tube,
which is made of such length as may be required, and securely fixed
stationary by a screw or other equivalent to the socket part.
While the essential nature of these improvements consists in con-
structing the rods of pyrometers (formed of different metals, and which
give the first or primary motion through the difference of their expansion
and contraction proportional to the different degrees to which they are
heated and cooled) of two long light bars or bands of brass and iron (or
other different metals used for the said purpose), and soldering or other-
wise fixing them effectually together as one composite solid bar, and then
twisting it like the body of a screw auger, or like a spiral spring, and in
the first instance in fixing the lower or extreme end of it to the extreme
end of the before-mentioned usual strong enclosing and protecting iron
'tube, with holes round it to admit the heat, while the other end has the
first motion spindle secured on it, with the toothed sector or crank lever
and pin on its upper or outer end, beyond a steady journal bearing in the
stem or swivelling eye or socket of the case containing the works and
dial. But when this new composite spiral spindle is made in the form
of a spiral or helical band or spring, then its one end is fixed to the
stationary hollow protecting tube, while the other is attached to a central
spindle, which may in this case pass up or out through the centre of the
composite spindle, which would communicate the rotary motion given
to it (by its expansion and contraction in heating and cooling) to the
said central spindle, turning freely on bearings at either end of the tube,

page_text: and which would through the crank and sector give rotary motion to
the index hand as before stated. Thus when the new spiral spindle or
coil (at the far end of the stationary tube) is subjected to heat, the brass
expanding considerably more than the iron causes the spiral to turn or
twist round in the tube to which it is fixed at the one end, and as the
spiral is fastened by one end to the central spindle it moves round along
with it, so as to give the said motion to the hand or pointer which
indicates the temperature upon the dial, and as it cools brings back tho
pointer to zero; or by another arrangement the toothed sector might be
fixed on it direct without the crank and pin or slotted arm; or motion
might also be given to the hand or pointer direct by fastening it upon
the central revolving spindle of the spiral coil, or the free end of the
spiral coil itself when the spindle is dispensed with, and the coiled bar
is made long enough for that purpose.
In either case or modification of this new or improved pyrometer the
action is caused by the extra twisting or untwisting of the composite
metal bar in proportion to the differential expansion of the two metals of
which it is composed by the heat imparted to it, which circular motion
the free turning spindle of the spiral bar communicates to the toothed
segment and pointer or index direct, so as to cause it to move in a forward
or backward direction over the index plate, which is divided in a circle
or segment and marked in equal divisions for degrees of heat in the
usual manner.
The advantages of these improvements are the greater length of bar
obtained by coiling the metal, thus giving a greater amount of expan-.
sion, and also the transmitting of a direct revolving or circular motion to
the pointer, which is turned forwards and backwards by the expansion
or contraction of the spiral band without the use of the usual returning
spring for that purpose.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighteenth day of May, in the year of
our Lord One thousand eight hundred and seventy-five, in the thirty-
eighth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Robert James Wood, Her special
licence that I, the said Robert James Wood, my executors, admini-
strators, and assigns, or such others as I, the said Robert James
Wood, my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man, an
Invention for "IMPROVEMENTS IN PYROMETERS," upon the condition
(amongst others) that I, the said Robert James Wood, my executors
or administrators, by an instrument in writing under my, or their,
or one of their hands and seals, should particularly describe and
ascertain the nature of the said Invention, and in what manner the
same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately
after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Robert James Wood, do hereby
declare the nature of my said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained
in and by the following statement in writing, reference being had to the
several figures and letters on the accompanying Sheet of Drawings, which
I have hereunto appended for the purpose of showing the nature of my
said Invention and best modes and means I am at present aware of for
performing or carrying it into effect or practice, the same reference
letters indicating the same or like parts in all the Figures where shown,
that is to say :-
Figure 1 is a sectional elevation with parts in the middle of the long
protecting and heating stem as broken away, and Figure 2 is an end or
face view of the index dial and pointer, all full size to show the details
more clearly, of one modification of my Invention, or of a pyrometer
having its parts constructed and arranged in accordance with and
illustrative of one modification of my improvements or Invention; and
Figure 3 is a complete half sized elevation with the retaining case or
stem in section of the same pyrometer, shown in Figures 1 and 2.

page_text: Referring generally to these Figures 1, 2, and 3, the construction of
the instrument is very similar to some other pyrometers, having a dial
a², with graduated circular or segmental divisions a, indicating degrees
of heat, with an indicating hand or pointer 6 on a spindle 6' (with
pinion as at 6", not shown in the Drawings), central or concentric to the
divisions a of the dial, in accordance with one modification of these
improvements, actuated by a corresponding toothed sector or segment,
either fixed in accordance with these my improvements on the prime
motion spindle B, or on a centre or stud carried on a small double armed
bracket, as 61 (shown carrying the index spindle in the Drawing), made
to swivel round the index spindle 6'; so that it can be set and fixed to
give more or less throw of the segment and index 6 over the dial a¹ to
exactly suit the divisions a, in the first instance by "trial and error,'
in shifting the axis of the sector laterally out of line with the axis of the
first motion spindle B, which in this case is connected by a short crank
with crank pin B', B³, working up into the slot of a short arm or
crank 6', fixed on the same axis as the toothed sector, so as to actuate it,
but shown in the modification of the Drawings as fixed on the index
spindle b, all which indicating mechanism is contained within the usual
hollow brass or other protecting casing a", with glass cover a", having
a new construction of short hollow stem C, with screw wheel E on it
carried in a socket piece C', with lateral screw spindle E' working in
the screw wheel E, and having a thumbscrew E" outside for turning
the case a¹¹ with the said gearing and dial round on the axis of the first
motion shaft B to adjust or set the hand or pointer 6 to the zero point
of the dial without turning the ordinary outer protecting tube D, which
is made of such length as may be required and securely fixed stationary
by a screw or other equivalent at c¹ to the socket part C¹.
The essential nature or new feature of these improvements consists
in constructing the expanding and contracting rods of pyrometers of
different metals (which give the first or primary motion through the
difference of their expansion and contraction proportional to the different
degrees to which they are heated and cooled), of two long light bars or
bands A, A¹, of brass and iron (or other different metals used for the
said purpose), and soldering or otherwise fixing them effectually together
as one composite solid bar, and then twisting it like a spiral spring or it
might be like the body of a screw auger.
Under one modification the lower or extreme end of the composite

page_text: spiral bar A, A¹, is fixed to the extreme end of the before-mentioned
usual strong enclosing and protecting iron tube D, at D", which has
holes D' round it to admit the heat, while the other end of this bar is
secured to the inner end of the first motion spindle B at B", with the
crank lever B and pin B² on its upper or outer end (or with the toothed
sector not shown in the Drawings), beyond a steady journal bearing in
the stem or swivelling eye or socket C of the case a" containing the
indicating mechanism and dial. When this new composite spindle or
bar A, A¹, is made in the form of a spiral or helical band or spring then
its inner end may be fixed to the stationary hollow protecting tube D,
while the other or lower end would be attached to the central spindle B,
which in this case would pass up or out through the centre of the
composite spindle or bar which communicates the rotary motion given
to it by its expansion and contraction in heating and cooling to the said
central spindle, turning freely on bearings at either end of the tube D,
so as to give through the crank B³, B³, or toothed sector rotary motion
to the index hand b, all as before stated. Thus when the new spiral
spindle or coil A, A¹, (at the far end of the stationary tube D) is
subjected to heat the brass expanding considerably more than the iron
causes the spiral to turn or twist round in the tube to which it is fixed
at the one end, and as the free end of the spiral is fastened to the
central spindle this moves round along with it, so as to give the said
motion to the hand or pointer b, which indicates the temperature upon
the dial a, a, and as the coil A, A¹, cools again it brings back the
pointer to zero or to the temperature of the atmosphere or place where
the instrument is situated; or by another arrangement the toothed
sector might be fixed on the spindle B direct without the crank and
pin B³, B³, or the slotted arm 6²; or motion might also be given to the
hand or pointer direct by fastening it upon the central revolving spindle
B of the spiral coil A, A¹.
In either case or modification of this new or improved pyrometer the
action is caused by the twisting or untwisting of the composite metal
bar A, A', in proportion to the differential expansion of the two metals
of which it is composed by the heat imparted to it, which circular
motion the free turning spindle B.of the spiral bar A, A', communicates
to the pointer or index 6, either through the toothed segment or duplex
cranks B¹, B², and 62, or direct to the pointer, as before stated, so as to
cause it to move in a forward or backward direction over the index plate

page_text: or dial a, a¹, which is divided in a circle or segment, and marked in
equal divisions for degrees of heat, Fahrenheit, in the usual manner, but
of course it might be in any other scale, as that of centigrade or
Reaumur.
Referring particularly to the construction and arrangement of the
parts of pyrometers or modification of my improvements shown in
Figures 1 to 3 on the accompanying Drawings a is the divided are on
the dial a¹, indicating the degrees Fahrenheit from 0° up to 800°, but
this may be varied for particular purposes, and higher temperatures
when desired. This dial is secured inside the upper edge of the hollow
case a¹¹ with the index or pointer 6 secured on the top of the short
spindle 6¹ working up through the dial, the pointer working freely over
the divided dial and below a protecting or covering in glass a¹, the
spindle 6' being carried in the two-armed bracket 61 screwed to the
inner surface or bottom of the case a", with the axis of the short
spindle 6' nearly in a line with that of the first motion spindle B steadied
by a bearing in the neck of the duplex or differential setting stem and
socket C, O', the former screwed at c to the under side of the case a", and
at c₁ to the upper end of the fixed retaining hollow stem D of the
spindle B of its new or improved expanding and contracting composite
metal bar or coil A, A', securely rivetted at its upper end B" to the
spindle B, and at its lower end to that of its retaining hollow stem D at
D", seen more particularly in Figures 1 and 3. The upper end of the
turning or moving spindle B has the short crank B', B', pinned or other-
wise fixed on it, having its long crank pin B³ working up into the slot of
an open or slotted throw crank 62 fixed on the lower end of the index
spindle b', so as to turn the index or pointer b over the divided arc of
degrees proportionally to the motion given to the crank B¹, B³, by the
expansion or contraction of the coil A, A', while being heated or cooled
respectively, the long crank pin B3 admitting of the longitudinal expan-
sion of the coil without action or injury in that direction to the free
turning of the spindle or crank 61, 62, moved by them.
The proper fixing of the case all to the stem C by the screws c
determines the differential proportion of the throw of the crank 6 by
setting its axle 6 more or less out of line with the axle B to make the
pointer indicate the exact degrees a¹ on the dial for the true degrees of
heat imparted to the acting coil A, A.. The hollow stem piece C
carrying the indicating dial turns. loosely in the hollow socket part C'

page_text: formed in halves and bolted together at c² to receive and hold it steadily,
and at the same time admit of its being turned by the screw wheel E
fixed on it and a worm wheel working in it on the spindle E¹, all within
the hollow socket C³, C¹, and turned by the thumbscrew E" on the
spindle E¹ outside the socket so as to set and hold the dial and pointer
of the index in their true normal or zero position ready for use, small
holes D¹ being formed at the lower end of the retaining case D opposite
the composite coil A, A¹, to admit the heat thereto, when this end of
the pyrometer is inserted into the material or chamber of which the
temperature is to be taken and indicated on the dial a, a', by the
pointer 6, which in this case turns in the opposite direction to the hands
of a clock when giving high temperatures, and vice versa when giving
low temperatures, the composite coil A, A³, being made of a thin band
of brass A outside and a band of iron or steel A¹ inside, coiled as a
right-hand screw, which by reason of the greater expansion of the brass
outside causes the upper free end B" to coil or twist under the influence
of heat and uncoil in cooling in the directions stated and indicated on
the dial a, a¹. The retaining case D is protected by a loose outside
sheath or close-ended tube z, easily withdrawn when the instrument is to
be used. When the intermediate transmitting pinion and toothed sector
are used between the spindles 6' and B then it is the axis of the sector
which must in the first instance be set and fixed out of line with the
axis B (by its carrying bracket) instead of the spindle 6¹ to make the
pointer and divisions on the dial true.
Although the motion has been described as transmitted from the
composite metal spiral bar A, A³, to the pointer or index 6 with the
divided dial fixed it is to be understood that the converse may be done
to effect the same purpose by fixing the pointer to the stationary case a¹¹
and moving the divided index or dial a, a¹, by attaching it to the
spindle B or to a bollow or other spindle turned on the axis or centre 6¹
of the pointer b and turning it instead of the pointer, as shown and
described.
The advantages of these improvements are, the greater length obtained
by coiling the composite metal bar A, A¹, which gives a greater amount
of expansion and circular motion; also the transmitting of a direct
revolving or circular motion to the moving spindles and pointer 6 which
is turned forwards and backwards by the expansion and contraction

page_text: respectively of the spiral band A, A¹, without the use of the ordinary
reacting returning spring for that purpose.
Having now described and particularly ascertained the nature of my
said Invention, and the manner in which the same is to be performed,
I have to state that I do not restrict myself to the precise details herein
described and delineated; on the other hand there are many of these
details which I do not desire to claim separately or by themselves as
they may have been used heretofore; but what I consider novel and
original and therefore claim as the Invention secured to me by the
herein-before in part recited Letters Patent is,-
First. The general construction and arrangement or combination of
the parts of pyrometers all substantially in the new or improved manner
herein described in reference to and shown in the accompanying
Drawings, or any mere modification thereof.
Second. The constructing of pyrometers with their primary motive or
expanding and contracting bars made of two sheets, bars, or bands of
different expanding metals, as of iron or steel and brass, soldered,
rivetted, or otherwise secured together, and made or twisted in the form
of a screw, helix, or scroll so as to produce and transmit a circular
motion direct to the indicating mechanism and pointer or divided dial,
all substantially as herein described in reference to and shown in the
accompanying Drawings, or any mere modification thereof.
In witness whereof, I, the said Robert James Wood, have here-
unto set my hand and seal, this Sixteenth day of November, in
the year of our Lord One thousand eight hundred and seventy-
five.
Witness,
W. R. M. THOMSON,
Patent Agent,
Glasgow.
ROBERT J. WOOD. (L.S.)