Glossary A – B

*terms marked with an asterisk appear in this glossary

ACCELERATING BEAM – a scale beam which, when moved from the horizontal position, continues to move with accelerated velocity to its position of maximum tilt, where it remains until unloaded. Scales with this type of beam were used for rapid weighing where precision was of secondary importance, as for example in weighing coal. Also called an UNSTABLE WEIGHBRIDGE (USA). See also VIBRATING BEAM. 

ACCURACY – the degree of agreement between the measured weight and the true weight (USA). 

ADJUSTING HOLE – a hole in the underside of a weight into which a lead plug was fitted for adjustment to the standard. Also called an ADJUSTMENT CAVITY (USA). 

ADJUSTMENT CAVITY – see ADJUSTING HOLE. 

'A’ FRAMES — the metal frames supporting the beam of Roberval* letter scales, or similar instruments, Fig. 1.

A.G. –  Abgezogen Gewichte (German) = adjusted weight. See also R.A. 

AGATE BEARING — a bearing* made from hard igneous rock and used for the pivots* of good quality small scales and precision balances where resistance to corrosion was particularly important Fig.  2. 

AGATE BOX — the housing for an agate bearing*, typically seen on English shop scales, Fig. 2. See also SHARKEY END. 

ANALYTICAL BALANCE — a sensitive scale used for the analysis of materials in a laboratory. See also PRECISION BALANCE.

ANTI-FRICTION PLATE — a small plate of hard metal at the end of a bearing* which resists the sideways motion of the knife edge,* Fig. 2.
Colloquially called "FRICTIONS" in England. Also called a THRUST PLATE, END PLATE, or END FRICTIONS (USA). 

APPROVAL SEAL — see VERIFICATION MARK. 

ARM — the distance between the main fulcrum* and a beam end pivot.* Fig. 3. See also EQUAL-ARM BEAM, UNEQUAL-ARM BEAM. 

ARRESTMENT GEAR — a mechanism that prevents movement of scale pans when they are not in use. It is commonly seen on precision balances* in the form of small metal pads which rise up from the base below each pan, Fig. 4. See also RELIEVING GEAR. 

ARROW SCALE — a scale used in England for weighing the arrows for an archery contest in the 18th c. The receptacle for the arrow was a slender channel suspended by four cords, Fig. 5.

ASSAY BALANCE — a sensitive scale used in the analysis of gold, silver, etc. to determine their purity or degree of alloying. Also called in old documents an ESSAY BALANCE. See also PRECISION balance.

AUTOMATIC SCALE — a scale for industrial weighing which loads, weighs, and discharges automatically. See also FOLDING GOLD BALANCE. 

BALANCE —

  1. The name for a weighing instrument said to be derived from bi-lanx, the Latin for two pans. See also SCALE.
  2. A state of equilibrium. 

BALANCE BALL —

  1. A weight used to adjust the balance of a beam before weighing, often in the form of a knurled nut on a threaded rod at the end of the beam, Fig. 7a.
  2. A hollow metal ball suspended from the end of an equal­ arm beam, or a steelyard. Lead shot is placed in the ball by scale adjusters for the adjustment of the balance, Fig. 7b. 

BALANCE BOX — a metal box fitted to a scale beam, or other moving part, and used to contain lead shot for adjustment of the balance. Also called a LOADING BOX (USA).

BAND — a metal belt used to transfer motion between parts of a weighing mechanism, usually connecting the beam to the indicator*. Also called a RIBBON or TAPE (USA). 

BEAM – a bar, or lever, suspended from a fulcrum* and carrying load pans, weight pans, hooks, etc. Also called a SCALEBEAM or WEIGHBEAM (USA). 

BEAM END — the fitting at the ends of a scale beam from which loads or weights are suspended. Various designs are shown in Fig. 6.

  1. Cord pivot end* 
  2. Trumpet end* or Lotus end*                            
  3. Ring-and-hole end* 
  4. Hook end* 
  5. Renaissance trumpet end* 
  6. Nuremberg end 
  7. Swan neck end* 
  8. German swan neck end 
  9. German rivetted swan neck end.                      
  10. Nuremberg swan neck end.
  11. Double hole end* 
  12. French double hole end. (It has a knife edge between the holes.)
  13. Open double hole end.
  14. Horned hole end.
  15. Open box end.
  16. Boxed swan neck end.
  17. Box end*
  18. Nuremberg box end.
  19. Swan box end.
  20. Spanish box end.
  21. Cusp box end.
  22. Berlin box end.
  23. Dutch end*
  24. Sharkey end*, or Agate box end.
  25. Stirrup end.
  26. Inverted swan neck end*
  27. Shackle end*

BEAM SCALE — In England, an equal-arm beam with hanging pans.
- In America, a steelyard.

BEARING — the special surface on which a knife edge* or pin pivot rotates. It is often a concave or vee surface made from hardened steel or agate,* Fig. 2, or it is in the form of a hard steel bush* Fig. 1. Some bearings may be simply a plain hole, as used on postal pendulum balances* with pin pivots.

BENCH SCALE — see COUNTER SCALE.

BERANGER SCALE — a scale constructed on the principle patented by Joseph Beranger in 1847. The load and weight plates are supported above the beam by a series of parallel linkages designed to eliminate side forces on the knife edges (a disadvantage of the Roberval* system), Fig. 8. 

BILATERAL PENDULUM SCALE — see PENDULUM SCALE.

BISMAR — an unequal-arm beam on which the weight and load hook have fixed positions. Equilibrium is attained by moving the fulcrum which is often in the form of a loop of cord, Fig. 9. The divisions* become closer together as the graduations* progress from light to heavy values, thus rendering the instrument inaccurate for heavier loads. Some modern bismars have, instead of a cord, a saddle* which slides along the beam, Fig. 9. 

BLADE — that part of a steelyard* beam which normally carries the graduations; the long arm between the fulcrum* and the nose* Fig. 9. 

BORDA WEIGHING — see SUBSTITUTION WEIGHING.

BOSS — the enlarged part of the beam through which a knife edge is fixed, Fig. 3. 

BOX END — a beam end on which the knife edges are enclosed in a box-like housing in order to protect the pivots from dust and damage, Fig. 6. 

BRAIDED CORD — a cord having a plaited sheath over a central core of strands, usually made of silk. It was used on small hand-held scales for weighing coins, medicines, etc.  See also TWISTED CORD.

BREVETÉ — patented (French). 

BUSH — a hard metal bearing set into soft metal to reduce wear. e.g., a hardened steel bush, or ring, is set into brass shears,* Fig. 1.

BUTTON PIVOT — see CONE PIVOT. 

BUTTON BALANCE — an assay balance* so-called because of the tiny button­ shaped blobs of gold etc. which were required for analysis.

A–B