drum chronograph
Datecirca 1892
Inventory Number1997-1-1847
ClassificationChronograph
Subject
Cultural Region
Place of Origin
Dimensions30.5 x 54 x 25.3 cm (12 x 21 1/4 x 9 15/16 in.)
Material
Accessoriesduplicate of nameplate (1997-1-1847b); pulley
DescriptionA weight driven gear train with governor, set in a heavy brass box, drives the drum and lead screw fixed in a cast iron track for the pen drive. The whole instrument is mounted on a heavy cast iron base. The gears from the gear-driven mechanism are cast in bronze, painted and then machined. The brass used in all other parts is from conventional rolled brass stock. There is a stop or hand break actuated by an outride handle lever, which impinges against a crown wheel. The latter has teeth on a rim to transfer the motion at right angles. The crown wheel in this instance drives the spindle directly with the fly-ball governor.
In Collection(s)
Signedon base: International Instrument Co / Cambridge, Mass
FunctionThe system found on this chronograph was the earliest practical method of recording operations to one hundredth of a second. A piece of paper specially cut is wrapped around the drum and secured with thumb screws. As the drum revolves slowly owing to the clock mechanism, a fountain pen is clamped in the bracket to hold it against the paper and to draw a fine line. The pen is moved slowly sidewise so the line does not run on top of itself. A contact on a second pendulum of a clock is wired (through a battery) to the electromagnet in the cylinder of the pen bracket. An impulse from the pendulum will then flick the pen to the left. It will show on the line as a little spur or peak and will repeat every second. An operator key or electrically- (or mechanically-) operated switch connected in parallel with the clock may also flick the pen. An electromagnet of a pair of coils is associated with the governor. An impulse fro mthe clock is the clock is also directed to the coils and this helps control the drive mechanism and can be adjusted so the second flicks of the pen occur quite regularly.
Historical AttributesAccording to David P. Wheatland, "This machine was one of the three selected as being the oldest and by the same manufacturer. The various chronographs obtained from Cruft, Lyman, Jefferson and astronomy are by several makers but there were three almost alike and the older one of these preserved and restored externally by John Losch March 16, 1965. The other two later machines had minor differences, which were construction changes to overcome certain difficulties encountered with this one."
International Instrument Company
Date: circa 1892
Object number: 1997-1-1847b
E. Zimmermann
Date: 1890-1910
Accessories: weights, crank, extra tuning fork
Object number: WJ0105
Thomas Hall
Date: circa 1890
Accessories: pulley rope
Object number: 1997-1-1423
Hans W. Egli
Date: circa 1925
Accessories: brush
Object number: 1996-1-0166
