Chrongraphs

Along the same lines as the seismography investigation, I am looking into the measurement of time, and the chronograph seems as good a place to start as any... All I currently know is that it looks like an incredibly complex instrument with an infinitude of tiny cogs... let's see what else can be learned...!

The Greek words "chronos" and "graph" stand for "time" and "writing". A chronograph is a chronometric (time-measuring) device which contains a mechanism that allows to stop at least one hand to facilitate reading of the elapsed time.The chronograph was invented by a Frenchman, named Rieussec, back in 1821. Literally, this was the only timepiece that bore the name Chronograph rightly. It was actually written on the dial with a small pen attached to the index. The length of the arc of the circle displayed the time that had passed. The index was fixed, while the dial turned. In 1822, Rieussec was granted a patent for his invention.

Chronographs are watches that can meassure time in different ways. Besides normal timekeeping, they can be used for one or more specific time measurements. For this, the dial has several sub dials with a scale, from which the measurements can be read. A central second hand can be started and stopped, without interfering with the continuous time.

The design of the dial of chronographs depends on the number of subsidiary dials. This can be two, three or even four. One of them is likely to be situated on the "9" of the dial, and shows the continuous seconds. When the chronograph is activated by pushing the top button, the central seconds hands starts moving. After one complete cycle is completed and the hand has returned to "12", the minute-indicator, located at the "3", will jump one position. With this simple type of chronograph a period of 30 or 45 minutes can be measured.

More complicated chrono's have a subregister for total hours, often located at 6 o'clock on the dial. This enable to take measurements up to 12 hours. Even fairly simple chronographs have a very complicated movement.

The escapement of a watch is that mechanism which operates in a very precise manner in order to release increments of time through the gear train of a watch. The Straight Line escapement from the Fredonia Watch Company. Many companies used the term "Equi-Distant" escapement when describing the type of escapement used in their watches. This is interesting as all escapements commonly found in pocket watches used and equidistant escapement. The escape wheel is round and has 15 teeth. The pallet has two impulse jewels which by obvious terms divides the escape wheel into a circular operation, thus becoming an equidistant escapement.

The diagram above shows the typical gear train of a watch. The escapement of a watch begins with the escape wheel. Next you will have the pallet. The pallet makes contact with the balance wheel as shown in the diagram. The balance wheel swings back and forth and with each swing locks and unlocks the pallet as it engages the escape wheel. This arc-of-motion can range from 18,000 beats per hour to as much as 28,000 beats per hour on some wrist watches.