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Horological

Dictionary

• A
  
  

  Action:

  A term used to denote the extent of the arc of vibration of the balance, or pendulum.

  Annealing:

  A process of heat treatment for reducing the degree of metal to give it maximum malleability or ductility.

  Ayr-Stone:

  A bluish-gray stone used with water to make a paste to add a finish to brass or other soft metals.

  Abacus:

  The uppermost member of the capital of a column.

  Albert:

  A watch chain, used as a means of attaching a pocket watch to a garment. Named after albert, Prince Consort.

  Arkansas Stone:

  A fine grained, hard, whitish stone ( Silicone) used for whetting tools to a fine edge.



• B
  
  

  Back Cock:

  The pallet cock of a pendulum clock. The term applies to both Anchor and Crown Wheel escapement clocks.

  Backslope:

  the part of the balance staff which tapers from the balance on the underside: also refers to the cut at the back of a balance staff pivot.

  Banking:

  when applied to the lever escapement, it is that part on which the lever rests or "banks".

  Belfrey:

  The hood of a tall case clock in which the movement is cased.

  Biseau:

  A bevel. In Horology it refers to the plates of a watch movement which have been bevelled to make the movement thin on the edge: a biseau movemnt.

  Bread:

  Bread was used by the old English finishers as a means of cleaning the work during polishing. It is more efficacious than pith. The center portion of a piece of bread, without the crust, about the size of a golf ball was kneaded up with oil to the consistency of putty and used by dabbing on to the work.

  Bridge:

  A bracket with two feet commonly used to support the pivot of an arbor outside the plates of a clock.

  Bulls Eye Door:

  A circular orifice in Tall Case clock doors. It permits the view of the pendulum swing.

  Butterfly:

  A cutout in the plate of a pocketwatch. This allowed for easier adjustment of the escapement. This design was utilized by the U. S. Watch Co.



• C
  
  

  Calotte:

  A type of watch case which fits into a folding case; also know as a "Portfolio". The outer case, usually made of leather, is the portfolio and the time-piece and its metal case is the Calotte.

  Channelling

  An operation where grooves ae cut into woodwork to form a pattern.

  Cheeks:

  The part of a long case clock upon which the Seat board rests.

  Civil Time:

  Two 12 hour periods starting at midnight.

  Crossings:

  A clockmaker term for the spokes of a wheel. Good quality clocks usually have 5 or more "crossings" in their wheels.

  Chops:

  A term for pieces of wood or soft metal used to protect work held in a vise. These are also known as "Clams".

  Counterpoise:

  A method of counter balancing. A weight attached to the hour or minute arbor of a turret clock to counter balance the weight of a heavy hand.

  Crocus:

  A iron oxide used in polishing brass or steel. Rouge is a refined grade of crocus.

  Cuvette:

  the dust cap for a watch.



• D
  
  

  Daily Rate:

  The amount that a clock or watch gains or loses on correct time. A gaining rate is shown as +, and a losing rate is shown as -.

  Diamantine:

  A white powder that when mixed with a small amount of oil is used for finishing and polishing steel.

  Dogs:

  The clamps or fixing pieces found on the face plate of the mandrel, uprighting tool, etc. ( see mandrel)

  Draw Plate:

  A plate with a series of graduated holes. It is used to reduce or draw down the diameter of round wire.



• E
  
  

  Ebauche:

  An unfinished movement, i.e. the movement in the rough before the escapement is fitted, or the train has been pivoted.

  Electromagnet:

  A magnet, the properties of which are exhibited under and dependent upon, the engergizing influence of an electric current.

  Endstone

  the jewell disc fitted to form the end of a hole, so that the end of the pivot can work upon it whereas without it, the shoulder of the pivot would take the weight or thrust. Ocassionally this is referred to as Jewel Cap, or endpiece.

  .



• F
  
  

  Facing:

  The process of finishing the ends of pinion heads.

  Flirt:

  A weighted or spring loaded lever which is wound by the going train and released to let off strike work.

  Frosting:

  The granular or matted finish given to a surface of brass clock parts prior to gilding.



• G
  
  

  Gadroon:

  A decoration resembling reeds or inverted flutes.

  Garter Back:

  A term that refers to the termination of engine turning employed on watch cases.

  Gilding:

  The process of coating a base metal such as brass with a very fine layer of gold, much used in watch-movement finishing. For clocks, it is mostly used to decorate external details.

  Gimbel:

  A device used in Marine Chronometer boxes to hold the movement horizontal no matter how a ship might roll or pitch.

  Gnomon:

  The pointer of a sundial which casts the shadow.

  Graver:

  A cutting tool of hardened steel, square or lozengeshaped in section and of varying thickness. One end has a tang for fitting into a ahndle and the other is ground off at an angle to obtain the cutting point or face.



• H
  
  

  Hipp-toggle:

  A mechanism developed by Matthew Hipp. The purpose is to maintain a pendulum in oscillation electrically.

  Hoop Wheel:

  A wheel in the striking train of an old type of clock. It has a brass edge or "hoop" attached to the side, extending about 7/8th of the circumference, and acts as the locking device for the striking train.

  Horse:

  A stand or bracket used to hold a clock movement while testing outside of the case.



• I
  
  

  Incabloc:

  A shock resisting system where the jewel holes and endstones of the balance "give" when the watch receives a shock. the spring like settings operate until a shoulder turned on the balance staff contacts a block and so takes the effect of a major shock.



• J
  
  

  Jewelled

  A term used in horology to define bearings or holes and surfaces made from jewel stones.



• K
  
  

  Kerf:

  A cut made by a saw, sometimes used as a form of decoration. Similar to some form of inlay work but without the inlay.



• M
  
  

  Maintaining Power:

  A mechanism for maintaining a clocks drive while winding.

  Mandrel:

  A faceplate fitted with "dogs" or clips to hold the work during turning, fitted to the lathe. or as a seperate self contained tool. In engineering, a mandrel is a bar set between centers to mount tools or work.

• O
  
  

  Ogee:

  A moulding: convex above and concave below, a continous curve.



• P
  
  

  Parting Out:

  The practice of taking a watch, original or not, and disassembling it, including, but not limited to, the case, the movement, dial, hand, and other components of the "watch" and selling the various components to profit over and above the value of the watch to "switchers", who to their liking by mixing and matching various movements, dials and cases to upgrade or improve the condition of their watch.

  Pawl:

  A device mounted on a oscillating arm used to advance a ratchet. Commonly known as a "click".

  Platform:

  A plate carrying a subassembly which may be removed for work without disturbing the main frame of the clock.

  Plinth:

  The lower part of a clock case upon which the case is built, also termed the base.



• R
  
  

  Recital Alarm Clock:

  An eight day alarm clock which repeats the alarm every 24 hours without resetting.

  Remontoire:
  A device used in higher quality clocks, which winds an auxiliary spring or weight. This winds the clock at shorter intervals to provide a more constant driving force for the escapement.


• S
  
  

  Shrouds:

  The caps or ends of the lantern pinion into which the pins or trundles are fitted.

  Snailing:

  A process which imparts a decorative finish to metal clock parts. The finish takes the form of curved lines begging from a common center,

  Stopwork:

  The mechanism used to limit the number of turns, either up or down, of a mainspring.



• T
  
  

  Tea-Time Clock:

  A type of alarm clock incorporated into a fixture with a specially designed electric kettle and a tea pot. At a predetermined time, the kettle is made to boil and pour the water into the tea pot. It is also called a "Teasmade".

  Toller:

  A single strike of a bell.

  Trundles:

  The wire "leaves" of a Lantern pinion.

  Tympanum:

  The arched section over the dial of a clock.

  Time:

  a:A moment, hour, day or year as indicated by a clock or calendar. b: Any of various systems ( sidreal or solar) of reckoning time.



• U
  
  

  Unlocking:

  The act of releasing. In horology, it is a term to define the release of a part or mechanism previously locked or inopereative. It is generally used in reference to the unlocking of the escape wheel, sometimes referred to as "discharging".



• W
  
  

  Wag-On-The-Wall Clock:

  An American term for a wall clock in which the pendulum and weights are exposed to view.

  Wig-Wag Tool:

  A tool so devised that a reciprocating or backward and forward motion is obtained; used for polishing pivots.

  Wings:

  The appendages on the sides of early clocks. These were used to hide the wide swing of a bob pendulum.



• Z
  
  

  Zappler Clock:

  A small pendulum clock made in Austria, in the early 19th century. the short light penfulum swings in front of the dial. Sometimes there are two pendulums swinging in opposite directions.

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