An Instrument for Measuring the Draught in Chimneys, Flues, and the like.
Year: 1895

page_text: Date of Application, 31st Aug., 1895-Accepted 12th Oct., 1895
COMPLETE SPECIFICATION.
An Instrument for Measuring the Draught in Chimneys, Flues,
and the like.
I, BERTHEL GEORG PAGH MÖLLER, of Kolding, Jutland, in the Kingdom of
Denmark, Publisher, 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 an instrument for measuring the draught in chimneys,
flues, and the like, and consists essentially of a counterweighted vane movable about
an axis within a cylindrical casing and combined with an index moving over a dial
by which the deflection of the vane under the influence of an air current induced
through the casing by the draught in the chimney or flue is indicated, the degree of
deflection being a measure of the strength of the current and consequently of the
draught.
Reference is to be had to the accompanying drawings, forming part of this
Specification, wherein
Figure 1 is a front view with the dial removed,
Figure 2 a side elevation,
Figure 3 a front view with the dial in place, and
Figure 4 a side view (partly in section) of the instrument.
The instrument comprises a cylindrical metal casing p within which is an easily
novable vane a carried by a spindle mounted centrally within the casing and prolonged.
through the front thereof to carry a pointer & which indicates the deflection of the
vane upon an empirically divided dial covered by a glass q. The vane is counter-
weighted by a bob g adjustable upon a screw threaded arm affixed to the blade
whereby the latter is caused to normally stand in the vertical position and the
casing is divided at the lower part from the periphery up to the axis by a fixed
partition d of which the vane forms, so to speak, an upward but movable
continuation whereby the casing is divided into two compartments m, n, which
communicate with each other only through the gap left between the edges of the
vane and the walls of the casing. The casing has an inlet e and outlet i at opposite
sides of the partition and communicating with the compartments m, n, respectively,
the outlet being adapted for connection with the chimney or flue, of which it is
desired to measure the draught. When this is done, the draught in the chimney
will induce a current of air through the instrument, the air entering at e, impinging
on, deflecting, and passing the vane, and passing out through i, the extent of the
deflection being indicated by the pointer on the dial and denoting the strength of
the current and consequently of the draught.
A hole is provided in the side of the casing at which a key c may be inserted
for adjusting the counterweight 9 before the outer casing is placed in position and
the partition d is so shaped as to permit the counterweight to hang vertically
beneath the vaue spindle when in its normal position. It is, however, to be
understood that a spring may be used instead of a counterweight.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:-
1. An instrument for measuring the draught in chimneys and the like, consisting
essentially of a vona nivated mevably within Boring Brovided with an inlet and

page_text: outlet for air between which the communication is so far blocked by the vane that
the latter will be deflected by a current of air induced through the instrument by
the draught, means being provided of indicating the extent of such deflection as a
measurement of the draught, substantially as described.
2. The instrument herein specified having a counterweighted vane pivoted upon
an axis central within the casing, a fixed division extending from the lower side of
the casing up to the vane axis and of such form as not to interfere with the normal
position of the counterweight vertically beneath the axis, and an air outlet at the
bottom of the casing at opposite side of the partition to the inlet opening so that
the air must necessarily pass through the upper part of the casing in which the vane
is movable, as specified.
3. In the apparatus herein specified, the pivoted vane counterweighted by a
weight adjustable by screwing along a threaded arm, the casing being provided
with an aperture for the insertion of a key whereby the adjustment of the
counterweight may be effected.
Tinted Anaust 31st 1805
A. M. & WM. CLARK,
53 Chancery Lane, London, Chartered Patent Agents.
A. M. & WM. CLARK,
53 Chancery Lane, London, Chartered Patent Agents.