Year: 1898

page_text: Date of Application, 5th Feb., 1898
Complete Specification Left, 2nd Nov., 1898-Accepted, 3rd Dec.,
1898
I, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co., Patent Agents,
45, Southampton Buildings, in the County of Middlesex, do hereby declare the
nature of this invention to be as follows;-
This invention relates to a novel mercury barometer of extreme sensibility,
which property is obtained by means of a special arrangement which I will
now describe.
The improved barometer consists of a small board or plate cut out for the
reception of a second plate which is capable of displacement along the first plate.
Such displacement is obtained by means of a micrometric screw mounted in sup-.
ports fixed upon the main plate and by means of a nut fixed to the sliding plate.
A capillary tube which is the barometric tube properly so called, is fixed upon
the main plate. It is bent above its point of attachment so as to form a hori-
zontal portion constituting the barometric chamber. This tube is sealed at its
extreme point and open at its lower extremity.
A second tube of larger diameter, which serves as a cup for the first tube is
fixed upon the sliding plate.
As will readily be understood from the foregoing description, it is only neces-
sary to displace the cup vertically in order to cause the barometric height to vary
and bring the mercury to the middle point of the horizontal portion after each
observation. If the annular section of the cup is, for example, ten times greater
than the section of the capillary tube, the movement of the mercury will be ten
It is the relation between these
times greater than the atmospheric variation.
This
two sections which is the measure of the sensibility of my barometer.
sensibility may thus be increased or diminished as desired by selecting tubes of
appropriate section.
Without changing such section, however, the sensibility may be increased con-
siderably by inclining the barometer; thus by inclining the barometer to the
extent of 200 its sensibility is doubled, the upper portion of the tube remaining
horizontal. In fact, if the atmospheric pressure increases to the extent of one
millimetre, the difference of level of the mercury will only increase by half a
millimetre. It is thus necessary that the mercury should traverse double the
distance in order that equilibrium may be established.
A graduated scale placed above the barometric chamber indicates the magnified
variations, in millimetres and fractions of a millimetre, of the atmospheric pres-
sure, of one observation to the preceding observation starting from the middle
point of the horizontal portion.
A second graduated scale arranged upon the sliding plate indicates in
con.

page_text: timetres and millimetres the total barometric heights. The index or pointer for
this latter scale is arranged upon the fixed plate.
The reading of the barometric heights is rendered capable of great precision,
by reference to the divisions upon the disc which forms a head for the adjusting
screw of the sliding plate.
For barometers of great precision the corrections relative to temperature may
be made without calculation, by means of a scale arranged beneath the baro-
metric chamber the divisions of which correspond to the expansion of the mer-
cury for each degree of the thermometer.
The correction relative to the form of the menisci of the mercury are likewise
made without calculation. It is only necessary, by acting on the screw, to cause
the mercury to pass the middle point and to bring it back to that point gently
and with a uniform speed.
My barometer is rendered portable by means of two india-rubber plugs. One
of these is placed at the bottom of the cup and stops the open extremity of the
tube upon raising the sliding plate sufficiently. The other plug which is fixed
around the tube is caused to bear upon the opening of the cup at the same time
that the bottom plug is brought against the tube.
Dated this 5th day of February 1898.
!
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
1, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
45, Southampton Buildings, in the County of Middlesex, 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 statement:-
-
This invention relates to a novel mercury barometer of extreme sensibility,
which property is obtained by means of a special arrangement which I will
now describe with reference to the accompanying drawing, in which:
Figure represents my improved barometer in vertical elevation, and
Figure 2 is a section upon the line -y of Figure 1.
The improved barometer consists of a small board or plate A cut out at A
for the reception of a second plate 1 which is capable of displacement along the
first plate A. Such displacement, is obtained by means of a micrometric
screw C mounted in supports C₁ fixed upon the main plate A, and by means of
a nut 6 fixed to the sliding plate B. A capillary tube D, which is the baro-
metric tube properly so called, is fixed at D¹ upon the main plate A. It is bent
above its point of attachment D¹ so as to form a horizontal portion EF con-
stituting the barometric chamber. This tube is sealed at its extreme point E
and open at its lower extremity.
A second tube G, of larger diameter, which serves as a cup for the first tube D,
is fixed at G¹G" upon the sliding plate B.
As will readily be understood from the foregoing description, it is only neces
sary to displace the tube G vertically in order to cause the barometric height to
vary and bring the mercury to the middle point M of the horizontal portion EF
after each observation. If the annular section of the tube G, is, for example,
ten times greater than the section of the capillary tube D, the movement of the
mercury will be ten times greater than the atmospheric variation.
It is the

page_text: relation between these two sections which is the measure of the sensibility of my
barometer. This sensibility may thus be increased or diminished as desired by
selecting tubes of appropriate section.
Without changing such sections, however, the sensibility may be increased
considerably by inclining the barometer; thus by inclining the barometer to the
extent of 20° its sensibility is doubled, the upper portion EF of the tube D
remaining horizontal.
In fact if the atmospheric pressure increases to the
extent of one millimetre, the difference of level of the mercury will only increase
by half a millimetre. It is thus necessary that the mercury should traverse
double the distance in order that equilibrium may be established.
A graduated scale I, placed above the barometric chamber EF, indicates the
magnified variations, in millimetres and fractions of a millimetre, of the atmos-
pheric pressure, of one observation to the preceding observation starting from M
the middle point of the horizontal portion EF.
A second graduated scale J arranged upon the sliding plate B indicates in
centimetres and millimetres the total barometric heights. The index or
pointer g for this latter scale is arranged upon the fixed plate A.
The reading of the barometric heights is rendered capable of great precision,
by refernce to the divisions upon the disc K, which forms a head for the adjust-
ing screw C.
For barometers of great precision the corrections relative to temperature may
be made, without calculation, by means of a scale O arranged beneath the baro-
metric chamber EF, the divisions of which correspond to the expansion of the
mercury for each degree of the thermometer.
The correction relative to the form of the menisci of the mercury are like-
wise made without calculation. It is only necessary by acting on the screw C,
to cause the mercury to pass the point M and to bring it back to that point gently
and with a uniform speed.
My barometer is rendered portable by means of two india rubber plugs. One
of these L is placed at the bottom of the tube G and stops the open extremity of
the tube D upon raising the sliding plate B sufficiently. The other plug N
which is fixed around the tube D is caused to bear upon the opening of the
tube G at the same time that the bottom plug L is brought against the tube D.
Having now particularly described and ascertained the nature of this inven-
tion 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 :-
A multiplying portable mercury barometer comprising two tubes, one of which
is a fixed capillary tube bent horizontally at its upper extremity so as to form
the barometrical chamber properly so called, whilst the other which is a tube of
larger diameter forms the cup and is mounted upon a plate capable of adjust-
ment by means of a michrometric screw, in such a manner that when the mer-
cury is displaced by means of the cup this displacement is multiplied in a atio
which is equal to the ratio of the annular section of the cup and that of the
horizontal capillary tube.
Dated this 2nd dow of Nonamh 1000
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.