IMPROVEMENTS IN JET PHOTOMETERS
Year: 1884

page_text: I ALFRED THOMAS of West Cowes in the Isle of Wight, Hants Gas Engineer,
Manager of the Cowes Gas Light and Coke Company, do hereby declare the nature
of my said invention for "IMPROVEMENTS IN JET PHOTOMETERS " to be as follows:―
This invention relates to means for measuring and indicating the illuminating
power of gas flames.
For the purpose of my invention I form a water tank and fix a partition mid-
distance within it but not reaching to the bottom. The lower end of this partition
has a double ended lever or beam jointed to it-for attaching by chains or other-
wise a float at each end. One float is free but the other has a thread attached and
this passes up out of the tank and is led over rollers and around the arbor of a
pointer or needle arranged in front of a dial the opposite end of the thread having
a counterpoise.
The two floats are within the tank and the gas is supplied on one side of the
partition and its pressure causes the water on that side to descend and that on the
opposite side to rise the floats altering their heights, moving the needle thereby.
I lead a pipe from the tank to a burner, the branch or stem of which has a long
screw thread for the adjustment of a collar carrying a wire, the top of which is
bent over the flame and is capable of being raised or lowered to suit the height
of flame.
For setting my apparatus or gas jet photometer in action I put water into the
tank till the floats are partly submerged both the floats then have an equal pull on
the beam below and until the whole of the extra water above the normal line
flotation has evaporated the float always pulls the pointer back to zero and so
produces an unvarying water line.
When the pointer is started at zero the gas is blown into the chamber that has
the free float and as the gas fills this chamber it presses the water down and
under the division plate.
The gas is allowed to enter till the second float has moved the pointer to a given
mark on the dial and then the length of flame is measured by a scale role made for
the purpose and the candle power is determined by its length as per "Suggs
system.
To gauge the height of the flame suppose the top of the light to be touching
the wire and the gas is 20 candle power; if the illuminating power is reduced to
18 cand'e the collar is screwed down the long screw the wire lowering with it till
the wire touches the light, the distance is measured by a scale rule which has the
number of candle power marked upon it.
י-

page_text: I ALFRED THOMAS of West Cowes in the Isle of Wight, Hants, Gas Engineer
Manager of the Cowes Gas Light and Coke Company do hereby declare the nature
of my invention for IMPROVEMENTS IN JET PHOTOMETERS and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
This invention relates to that class of apparatus for measuring and indicating the
illuminating power of gas flames known as Jet photometers and the invention
consists in certain improvements thereon whereby while allowing for a considerable
variation in the height of the water line, the zero point is automatically maintained.
In carrying out my invention I employ a pair of floats-which I place in a
- suitable vessel or tank. This vessel or tank is divided into two equal sized com-
partments by a central transverse vertical partition which by preference stops
short of the bottom of the tank. Suspended in any convenient manner from this
partition is a beam, to the opposite ends of which the floats are connected by chains
or otherwise.
The tank or vessel is filled with water to a given height above the floating line
of the floats and on gas being admitted to .c
.one compartment pressure will be
cxerted on the surface of the water in that compartment and some of the water
therein will be forced into the other compartment.
This will have the effect of altering the respective floating lines of the two floats
thus the first float will be lowered while the second will be raised.
The second float is connected by meaus of a cord with a pointer which will thereby
be moved to indicate on a dial the amount of pressure required to produce a flame
of a given length from a given sized jet.
As the amount of pressure required for that purpose will depend upon the
richness or poorness of the gas the pointer will also indicate the illuminating power
of the gas according to a prearranged calculation. When the pressure is removed the
pointer will automatically regain the zero. point and the use of special means for
adjusting and regulating the instrument will thereby be obviated.
In the accompanying drawing I have shown in elevation partly in section my
improved jet photometer.
A is the tank or vessel which may be of any convenient size B is the central
transverse partition which as will be seen stops short of the bottom of the tank
and divides the tank into two equal compartments A A¹, C is a beam which is
suspended at the centre of its length from the partition B or from any other
convenient point so that an arm will project on either side of the partition.
D D' are floats which are attached to the beam C by chains or other means. The
float D¹ is connected to a cord a which is passed over a small guide pulley b to and
round a pulley on the axle of the pointer E and thence over another guide pulley b¹
the free end being secured to a small counter weight c.
I may here mention that the connection between the float D' and pointer E may
be effected in any convenient and well known manner,
The axle of the pointer E has its bearings on a standard F which also carries an
indicating dial F¹. This standard also carries a vertical threaded tube G on the top
of which the gas jet G¹ is fitted. This tube G is connected in any convenient
manner with the compartment A of the tank or vessel and is provided externally
with a nut H. This nut H carries a wire gauge e which is intended to be set to
denote the standard height of flame required for a given quality of gas. Gas is
introduced into the compartment A through the opening f.

page_text: In order to set my improved apparatus ready for working I fill the tank unti
both floats are nearly submerged as indicated in the drawing the height of water
being by preference regulated by a waste pipe or other suitable means. The floats
will thus be maintained in equilibrium and will have an equal pull on the beam C
and the pointer will be maintained at zero.
Gas is then admitted to the compartment A and the jet G¹ is lighted. The
pressure of the gas will cause the water to descend in compartment A and rise in
compartment A' thereby altering the line of flotation and causing the float D¹ to
rise. The effect of this will be to slacken the cord a which under the influence of
the counter weight c will rotate the axle of the pointer E and move the pointer
across the dial F¹ until such time as the requisite amount of pressure (which will
be increased or diminished as required) to give the standard height of flame is
indicated.
By taking the reading on the dial and comparing it with a prearranged calcu-
lation the illuminating power of the gas supply can be readily ascertained.
The standard height of flame varies within certain limits according to the richness
of the gas that is to say the richer the gas the shorter is the standard height of
flame such flame being obtained at a comparatively low pressure.
The general working of jet photometers is however well understood and there-
fore further description is unnecessary the chief advantage to be derived from the
use of my improved photometer being that until the extra water above the normal
line of flotation of the floats has evaporated the zero point will be automatically
regained and maintained and the employment of special means, as in other
apparatus of this class for periodically adjusting and regulating the instrument
will be thereby avoided.
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:
In jet photometers the use of two floats attached to the opposite ends of a
rocking beam and working in separate compartments as and for the purpose
described.