5. Move the upper poise to the right until the
scale is brought into balance with the pointer in the center of the
dial or swinging an equal distance to the left and right.
6. Read the weight directly from the beams by
adding the amounts indicated on the upper and lower beams.
7. If it is necessary to weigh above the beam
capacity, place additional loose weights on the right platform until
the total of these weights comes to within the beam capacity range of
the weight of the specimen. The final balance is done by moving the
sliding poises on the beams. The weight of the specimen is repre-
sented by the total of the weights on the right platform plus the
(2) Analytical Balance.
(a) Description. The analytical balance (fig. 2-6)
is equipped with an automatic preweighing and single-knob taring
1. The balance has a full 1000-mg optical range
with all-digital readout. The numbers to be read on the optical
scale appear in a clear window; all neighboring valures are visible,
but subdued, through a green filter.
2. The balance also has simplified table-level
controls. Two knobs dial in the weights from 1 to 99 grams. The
release lever is turned down and the weight is read to the last
decimal place by superimposing a hairline on the optical scale with
the micrometer drum knob. The weight application knobs and readout
are arranged in a straight line, in their logical seuquence from
3. The pan, optical scale and controls are in a
single field of view.
4. Sliding glass doors on either side of the
balance provide access to the weighing chamber. A pan brake that
acts on the bridle above the chamber provides damping of pan swing.
5. The weighing beam is made of polished alum-
inum alloy and the knives are precision-ground sythetic sapphires.
All weights are cylindrical. The optical system is mounted in a
precision alignment mechanism, which has a focusing control for
maximum image sharpness. The projection system uses magnification
to provide the reading image and the best reproducibility. The
design principle is that of constant load (substitution) weighing.