IMPROVEMENTS IN THE MANUFACTURE OF THERMOMETERS
Year: 1885

page_text: I JAMES JOSEPH HICKS of 8 Hatton Garden in the County of Middlesex,
Meteorological Instrument Manufacturer do hereby declare the nature of the said
Invention for IMPROVEMENTS IN THE MANUFACTURE OF THERMOMETERS to be as
follows:-
.
It is well known amongst manufacturers and experts that thermometer tubes
for some time after the manufacture and filling thereof, are subject to a constant
gradual shrinkage which in time becomes so considerable, that if the thermometer
were divided and figured immediately after the manufacture and filling of the
tube, it would soon show a considerable inaccuracy which in some cases amounts
to a rise of one degree and even more within a period of 12 months.
It has consequently been the practice of manufacturers in order to produce
thermometers which shall vary but little after their manufacture, to store the.
thermometer tubes for months and even for years before pointing dividing and
figuring them. This involves in some cases a considerable amount of capital lying
idle in the shape of thermometer tubes which, combined with the breakages which
sometimes occur, increases the cost of production..
Now according to my Invention I avoid these difficulties and manufacturé
thermometers in a comparatively short time which are more permanent and less
liable to change in their indications than thermometers made of tubes which have
been stored for several years before being divided and figured.
In carrying my Invention into effect I take a length of tubing, blow a bulb on
to one end thereof, supply it with mercury or other fluid and close it in a similar
manner to that ordinarily adopted in the manufacture of thermometer tubes
taking care to leave an enlargement prolongation or chamber at the upper end of
the tube sufficiently large for the purpose hereinafter described.
I then submit such thermometer tubes to a prolonged annealing process which I
carry out in somewhat the following manner.
I submit the thermometer tubes for a period preferably of about 16 days to a
temperature above the highest point to which they are required to indicate say

page_text: :
f
from 50 to 150 degrees above such highest point. The temperature as also the
period during which the thermometer tubes are submitted to such temperature
may be varied. I however prefer to adopt those above stated but in all cases in
order to obtain the best results the annealing temperature must be above the point
to which the completed thermometer is required to indicate. In order to ensure
the thermometer tubes being submitted to as constant and unvarying a ten-
perature in the annealing chamber as is possible, I prefer to immerse them in
some liquid which is maintained at the required temperature for the required time,
being gradually raised to such temperature and gradually cooled before removing
the thermometer tubes therefrom.
For this purpose I have found linseed oil or mercury to answer well as they do
not injure the glass whilst if water were employed the glass would be rendered
rough and would consequently require to be polished after removal from the
annealing chamber.
The thermometer tubes may however be immersed in other liquids or media
during the annealing process or they may be placed in a close chamber without
any such liquid or media provided care is taken to prevent the ingress of cold air
to vary the temperature.
During the annealing operation the mercury rises in the tube to the enlarge-
ment, prolongation or chamber at the upper end of the tube and such enlargement
prolongation or chamber must be of such cubical contents as to give more than
sufficient space for the expansion of the mercury or other fluid thereinto without
risk of injury to the thermometer tube.
After the thermometer tubes have been treated in the manner above described
they are pointed, divided and figured in the ordinary way; if desired the enlarge-
ment prolongation or chamber at the upper end of the bore may be sealed off or
it may be allowed to remain as it will be of no detriment except in cases where it
is required to produce thermometers of the shortest possible length.
The following are the results of some of my experiments. I have found that by
submitting a number of thermometer tubes (which when completed were required
to indicate up to 120 degrees Fahrenheit) to an annealing process in a bath of
water at a temperature of 212° Fahrenheit for 16 days and then allowing them
gradually to cool, a rise of from one degree and 1 tenth to one degree and 8 tenths
has been produced in the indications of such tubes. I have found that by
submitting a number of thermometer tubes (which when completed were required
to indicate up to 212 degrees Fahrenheit) to an annealing process in a bath of
linseed oil or mercury at a temperature of 300° Fahrenheit for 16 days and then
allowed gradually to cool a rise of from 2 degrees and 6 tenths to
been produced in the indications of such tubes.
degrees has
I have also found that when submitting a number of thermometer tubes
(which when completed were required to indicate up to 220 degrees Fahrenheit)
to an annealing process in a bath of linseed oil or mercury at a temperature
of 300° Fahrenheit and then allowed gradually to cool, a rise in the indications of
such tubes has been caused during the first week of from one degree and 5 tenths
to 2 degrees and 4 tenths, during the second week a rise of 3 to 6 tenths, during
the third week a rise of from tenths to 4 tenths; during the fourth week a rise
of from 0 to 3 tenths and during the fifth week a rise of from 0 to 2 tenths, thus
showing that the greatest effect is produced during the first week of the annealing
process.
It will thus be seen that by my process, I cause much more contraction (nearly
double) of thermometer tubes in 16 days than the maximum contraction known of
thermometer tubes which have not been submitted to my process but which have
been simply stored for a period of one year or more before pointing, dividing and
figuring the same whilst in a single week I produce as much as, or somewhat
more, contraction by my process than the maximum known of simply stored
thermometer tubes.

page_text: By these means I produce thermometers which are practically or nearly invariable
after their completion, that is to say the column of which will always stand at the
same heights for given temperatures provided the thermometers are not submitted
to higher temperatures than those to which they are intended to indicate.
I JAMES JOSEPH HICKS of 8 Hatton Garden in the County of Middlesex,
Meteorological Instrument Manufacturer do hereby declare the nature of the said
invention and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement :-
It is well known amongst manufacturers and experts, that thermometer tubes,
for some time after the manufacture and filling thereof, are subject to a constant
gradual shrinkage, which in time becomes so considerable, that if the thermometer
were divided and figured immediately after the manufacture and filling of the tube,
it would soon show a considerable inaccuracy, which in some cases, amounts to
a rise of one degree and even more, above the correct indication within a period
of 12 months.
It has consequently been the practice of manufacturers in order to produce
thermometers which shall vary but little after their manufacture, to store the
thermometer tubes for months and even for years before pointing dividing and
figuring them. This involves in some cases a considerable amount of capital lying
idle in the shape of thermometer tubes, which, combined with the breakages which
sometimes occur, increases the cost of production.
Now according to my invention I avoid these difficulties and manufacture
thermometers in a comparatively short time, which are more permanent and less
liable to change or errors in their indications for given temperatures than thermo-
meters made of tubes which have been stored for several years before being divided
and figured.
In carrying my invention into effect I take a length of tubing, blow a bulb on
to one end thereof, supply it with mercury or other fluid, and close it in a similar
manner to that ordinarily adopted in the manufacture of thermometer tubes
taking care to leave an enlargement, prolongation or chamber at the upper end
of the tube sufficiently large for the purpose hereinafter described.

page_text: I then submit such thermometer tubes to a prolonged annealing process which
carry out in somewhat the following manner.
I submit the thermometer tubes for a period preferably of about 16 days to a
temperature above the highest point to which they are required to indicate say
from 50 to 150 degrees above such highest point. The temperature as also the
period during which the thermometer tubes are submitted to such temperature
may be varied. I however prefer to adopt those above stated but in all cases in
order to obtain the best results the annealing temperature must be above the point
to which the thermometer when completed is required to indicate. In order to
ensure the thermometer tubes being submitted to as constant and unvarying a
temperature in the annealing chamber as is possible, I prefer to immerse them in
some liquid which is maintained at the required temperature for the required time,
being gradually raised to such temperature and gradually cooled before removing
the thermometer tubes therefrom.
For this purpose I have found linseed oil or mercury to answer well, as they
do not injure the glass whilst if water were employed, the glass would be rendered
rough and would consequently require to be polished after removal from the
annealing chamber.
The thermometer tubes may however be immersed in other liquids or media
during the annealing process or they may be placed. in a close chamber without
any such liquid or media provided care is taken to prevent the ingress of cold air
to vary the temperature. During the annealing operation the mercury rises in the
tube to the enlargement prolongation or chamber at the upper end thereof and
such enlargement prolongation or chamber must be of such cubical contents as to
give more than sufficient space for the expansion of the mercury or other fluid
thereinto without risk of injury to the thermometer tube.
After the thermometer tubes have been treated in the manner above described,
they are pointed, divided and figured in the ordinary way; if desired the enlarge-
ment prolongation or chamber at the upper end of the bore may be sealed off or
it may be allowed to remain as it will be of no detriment except in cases where it
is required to produce thermometers of the shortest possible length.
The following are the results of some of my experiments. I have found that by
submitting a number of thermometer tubes (which when completed were required
to indicate up to 120 degrees Fahrenheit) to an annealing process in a bath of
water at a temperature of 212° Fahrenheit for 16 days and then allowing them
gradually to cool, a rise of from 1 degree and 1 tenth, to one degree and 8 tenths
has been produced in the indications of such tubes.
I have found that by submitting a number of thermometer tubes (which when
completed were required to indicate up to 212 degrees Fahrenheit) to an annealing
process in a bath of linseed oil or mercury at a temperature of 300° Fahrenheit for
16 days and then allowed gradually to cool, a rise of from 2 degrees and 6 tenths
to 3 degrees has been produced in the indications of such tubes.
I have also found that when submitting a number of thermometer tubes (which
when completed were required to indicate up to 220 degrees Fahrenheit) to an
annealing process in a bath of linseed oil or mercury at a temperature of
300° Fahrenheit and then allowed gradually to cool, a rise in the indications
of such tubes has been caused during the first week of from 1 degree and 5 tenths
to degrees and tenths, during the second week a rise of 3 to 6 tenths,
during the third week a rise of from 2 tenths to 4 tenths; during the fourth week
a rise of from 0 to 3 tenths, and during the fifth week a rise of from 0 to 2 tenths,
thus showing that the greatest effect is produced during the first week of the
annealing process.
It will thus be seen that by my process I cause much more contraction (nearly
double) of thermometer tubes in 16 days than the maximum contraction known
of thermometer tubes which have not been submitted to my process but which
have been simply stored for a period of one year or more before pointing, dividing

page_text: and figuring the same whilst in a single week I produce as much as or somewhat
more contraction by my process than the maximum known of simply stored
thermometer tubes. By these means I produce thermometers which are practically
or nearly invariable after their completion, that is to say the column of which will
always stand at the same heights for given temperatures provided the thermometers
are not submitted to higher temperatures than those to which they are intended to
indicate.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
The process of annealing thermometer tubes, after the same have been supplied
with mercury and sealed or closed, but before they have been pointed, divided and
figured, by submitting them for a considerable time to a temperature above the
highest point to which they are required to indicate, such thermometer tubes
being provided at their upper ends with enlargements, prolongations or chambers
to prevent injury thereto during the annealing process substantially as berein
described.