Maker, James Arthur. New York, USA, 1901, serial number 1 of 7.
Astronomical regulator with unique tri-dial design, Graham deadbeat
escapement with Wagner rocking frame, 60-second remontoire, one second
compensated pendulum, wheels and frame fabricated from bronze. Arthur made
seven of these, this being the first and having a dedication plate in honor
of his son Daniel Arthur, dated June 13, 1901. Three are known to survive
¹. Case dimensions 17.5"w x 81"h x 12"d.
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The drive weight is compounded substituting a conventional pulley with a
sphere, nested into the weight shell. Pendulum compensation makes use of
what may be a unique application of aluminum and steel. The external steel
pendulum tube is perforated, allowing the change in air temperature to
affect the internal pendulum parts faster and compensation to be made more
efficiently; originally employed by Edward Dent in the 18th century and
commonly known as the "tin whistle" design due to the look of the
perforations which often were round holes.
The dial work is one of the more unique features of this clock. All
astronomical clock dials have separate indications for the seconds, minutes
and hours. Usually this is all accomplished with three dial hands on three
sub-dials located on one overall dial plate. This clock uses three
individual dial rings forming an equilateral triangle to offer both a
visually striking contrast to a standard dial arrangement and to allow the
triangular-shaped skeleton movement behind them to be seen. The dial rings
are not of a conventional, flat design, but are a three-dimensional concave
shape and each has a different numeral style to readily distinguish amongst
them. Arthur used large diameter wheels that featured a wide variety of
spoke numbers; from four, to six, eight and even a wheel with ten spokes.
The first photo is of James Arthur at age 67. He wrote a book about his
horological interests in 1909. His clock is featured in the third
James Arthur was born February 26, 1842, of Scottish parents at
Crosscandley, Ireland. While he was still a child the family moved to
Glasgow where he attended the technical school and trained in mechanics,
metal and woodwork. At this early age he took an interest in horology and
made sundials and started restoring and collecting clocks and watches. In
November 1871 he came to the USA. His wife and the three older children
followed in 1872. James Arthur was a skilled mechanic with knowledge of
machinery and fine construction. Fourteen years after coming to the USA he
established the Arthur Machine Works at 188-190 Front Street, New York, for
the manufacture and repair of machinery and providing mechanical
models for inventors and gear designs for the nascent auto industry
He was a committed collector, who
also produced a number of clocks of which one design, constructed in 1901,
is worthy of consideration as a precision time piece. It is his astro-configured,
three dial, one-minute remontoire regulator illustrated here.
The predominant shape of the movement is that of an equilateral triangle.
The great wheel has 144 teeth, the second wheel has 80, and the pinion has
40. The hour wheel and the fourth wheel have 120 teeth and the pinions have
24. The idler wheel and the remontoire have 120 teeth and the escape wheel
has 30 and a 15 leaf pinion. The escapement is graham dead beat with
Arthur experimented extensively with aluminum using it for pallets and
wheels. His experiments met with little success. The material was relatively
new and absent of the appropriate alloying which would retain the light
weight, yet add the requisite hardness for such application. However, he
used aluminum effectively for pendulum compensation in this three-dial
remontoire regulator. The pendulum has steel side roods. The steel center
tube, perforated to facilitate rapid response to temperature change, encases
an aluminum ros which expands or contracts in opposition to the steel.
Arthur used involute gearing which provides a constant velocity ratio and is
not as sensitive to minor depthing variations. As with epicycloidal teeth,
the action takes place after the line of centers. Curiously, Arthur cut his
teeth ten percent deeper and sized the pinions one-quarter diametral pitch
smaller, but cut them to the regular depth ².
The meshing is somewhat shallow which would produce problematic backlash in
a fast moving train which, of course, does not to clock movements. However,
in Arthur's clock train, the space, resulting from this depthing, keeps dirt
of dust from getting trapped between the teeth. The plates are made of gun
metal and the clock runs for eight and one-half days. ³.
1. In addition to this example, one is in a private
collection on the East coast of the USA and one example belongs to the great
granddaughter of Arthur's other son John Forbes Arthur and two are in the
collection of the National Association of Watch and Clock Collectors (NAWCC)
Museum in Columbia, PA.
2. James Arthur,
Machinery, (November 1901), pp. 70-73.
3. Derek Roberts, Precision Pendulum Clocks, article by Donald Saff,