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Figure 1
above. A Japanese lantern clock (after restoration). | |
Figure 2,
below. The movement, with its Western-style count wheel. | |
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Figure 3.
Japanese time with English translation.2 |
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Figure 4.
Replaced count wheel from an American clock. |
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Figure 5.
Drawing for Japanese style count wheel. |
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Figure 8.
New Japanese count wheel installed. |
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Figure 9.
New copper sides and back with hinges and hooks. |
| My wife and I were on a recent vacation
and came across a clock shop outside of Boston. This shop was the largest
one I have ever seen and it was filled with many fine American and foreign
clocks. My wife asked which clock interested me the most, and I showed her a
Japanese lantern clock (see Figure 1). She was
surprised that I would pick this clock. The clock case was very simple
compared with the many fine tallcase, banjo, and shelf clocks found in this
store. Well, I am a collector who always likes something different to
restore and investigate. This clock fits those requirements—I could not even
tell what time it was when I looked at the clock or understand why there was
only one hand and 12 periods of time. Why did it have an American strike
wheel (Figure 4)? Why iron wheels and pinions? Why
were there no sides or back to the case? How do you set the time? How old is
it? There were more than enough questions to interest me, so I bought it.
The first step toward discovery was to bring it to my clock repair teacher
at the local technical college where I have been learning about clock repair
for the past seven years. We examined it closely and found it to be
controlled by a foliet and crown wheel (verge) escapement. The time and
strike trains are each powered by a separate weight and counterweight that
are not original to the clock. The wheels and pinions are made of iron and
the teeth show signs of hand filing. Some questions remained about its age.
Next, I brought it to a local mart and had some experienced members
review the clock and all seemed to believe it was an original. I also
visited a fellow member’s home and reviewed his collection, which included
some Japanese clocks. With his help, we compared my clock with some of his,
which again confirmed that this clock is an authentic antique.
Now was the time to check out all the books in English that I could find
about Japanese time and clocks from the NAWCC Library and Research Center.1-3
Japanese Time
The root source of Japanese clockmaking can be traced to gift
presentations made by Portuguese traders and missionaries to Japanese
dignitaries and merchants. The Dutch expulsion of the Spanish and Portuguese
in 1658 led to the Dutch style of clockmaking prevailing in Japan.4
The mechanical clock was a new concept for the Japanese, but their craftsmen
were very skilled in metalworking and adopted the concept. The Japanese
clockmakers modified the Dutch clock style to their own method of measuring
the passage of time.
The Japanese method of dividing the day originated in China. The day was
divided, from sunrise to sunset and from sunset to sunrise, into two
periods.2
The daylight period was divided into six intervals of equal length, and
the nighttime darkness was also divided into six equal intervals of
different lengths except on the equinox. The length of each Japanese hour
varied with the seasons, latitude, and even day to day. There are only 12
Japanese hours a day.
Figure 3 shows a facsimile of an early Japanese
clock dial; each of the 12 divisions has a numeral, corresponding with the
numbers of strikes on the bell and the 12 Chinese zodiacal signs associated
with that particular hour and their English translation. The Japanese method
was to start the beginning of the hour with a corresponding number of
strikes.3
The Japanese counted down their hourly strike, at a decreasing count. The
highest number, 9, was allocated to midday and midnight; because they only
required six numerals for each of the two periods of the day; 9-8-7-6-5-4
represent the progression of the hours. The numbers 1,2,3 were reserved for
the time-honored customs of the temple.3
The Japanese clock needed to have the balance weights adjusted from day
to night and from day to day, to correct for seasonal changes in the length
of daylight. The serrated arms of the balance are divided by vertical lines,
in groups of five, to aid in adjusting from day to night and throughout the
seasons.
Commodore Perry of the United States used gunboat diplomacy to open Japan
trade to the West. This led to the reintroduction of Western style
timekeeping, which became the official method of timekeeping in 1873.
Lantern Clock Dating
Japanese dating is very difficult because of a lack of written records,
as well as the time-honored tradition of continuing the manufacture in the
old proven methods handed down through the generations. This clock possesses
many characteristics of a very old lantern clock from the seventeenth
century. These include:3
- It is composed of all steel wheel work.
- The casing is devoid of ornamentation.
- The front plate is held to the frame by two tabs on the bottom and a
single screw above the dial.
- The back plate is held on with tabs and a single screw.
- The sides are attached to the back with hinges.
- The sides are held to the front dial with hooks into slits on the
front dial.
- The dial is made of copper plate.
- The bell is a beehive shape.
- The revolving central disk carrying the hand is held in place
with a single contoured nut.
- There is evidence of hand filing on the wheels.
- It has a single balance system.
- The Chinese zodiacal signs and corresponding numerals in gold are
inscribed on the front plate.2
Restoring the Count Wheel to Japanese Time
The count wheel that was found on the clock looks to have been recycled
from an American count wheel (see Figure 4). This
is a replacement from the original one, from a previous repairman who tried
to westernize the strike sequence. The count wheel rotates twice in a
Western 24-hour day. With each revolution from its 78-tooth drive wheel,
this count wheel allows the clock to strike with the Western method of
striking (i.e., 1-2-3-4-5-6-7-8-9-10-11-12, a total of 78 strikes per half
day) with a strike for every Western hour. This count wheel rotates on a
shaft, which was installed when it was converted from the Japanese strike
style. The original shaft had been removed.
The goal was to restore the strike to the Japanese method. This method
calls for a strike sequence of 9-1-8-1-7-1-6-1-5-1-4-1 for a total of 12
strike sequences and 45 strikes in half a day. A new count wheel, with 45
teeth, was installed to allow use of the original shaft hole. The count
wheel was drawn in CAD (see Figure 5). There are 45
strikes required in one revolution 360/45 or eight degrees per strike. A
three-inch-diameter circle was divided into eight-degree segments. The
cordal length on the OD between these eight-degree sections was 0.21 inches.
Each slot was made with the eight-degree slot plus 0.07 inches in each
direction for clearance fit of the count hook. Each slot is needed to stop
the Japanese hour strike and to allow for the next half-hour single strike.
This pattern was repeated until the entire half-day strikes were allowed for
on the count wheel, finishing the entire 360 degrees.
A steel sheet was cut and turned to three inches in diameter. Then a copy
of the CAD layout was glued to the sheet. The slots were then cut into the
sheet with a jeweler circular saw and table attached to a jeweler lathe, as
made in the F201 Field Suitcase Workshop (see Figure 6).
The new brass drive wheel was riveted to the new count wheel to complete the
new part (see Figure 7). The wheel was immersed into
a brass-tarnishing solution, which created a black oxidized appearance
similar to the rest of the clock. The count hook was adjusted to fit and
engage and disengage the strike mechanism from this count wheel (see
Figure 8).
Proper Weight Replacement
The original weights have been lost. The replaced weights were 2.9 pounds
with a counterweight of 1.1 pound. The resulting weight to drive both the
time and strike side was therefore only 1.8 pounds, a very small amount for
this size of movement. With these small weights the time movement would stop
when going into the strike mode, or the strike side would stop during the
lifting motion of the strike release even after cleaning and polishing the
pivots. I added small increments of weight until the clock ran well. Then
the total weight was measured and an equivalent weight was purchased and
installed at 4.2 pounds, which solved this problem without providing
unnecessary force on the movement—only 3.1 pounds.
Hinged Replacement Sides and Back
New 0.060-inch-thick copper sheet was purchased. The plate was cut to
size, and the edges were filed and all polished down with a wet emery cloth,
down to a 400 grit. New brass hinges were purchased through an online
catalog, and replacement hooks were made by copying an original. All
components were assembled by using Crazy Glue and were then drilled for
rivets. Brass rivets were made and peened over to attach hinges and hooks
(see Figure 9).
I would not have tackled a restoration project of this magnitude without
having taken the NAWCC Field Suitcase Workshop programs. These classes
provided a forum for learning many basic repair techniques, which I applied
in restoring this clock. The classes taught the investigative methods to
properly restore clocks and allowed students to build on the experiences of
others. Many thanks to all the instructors and supporters of the Field
Suitcase Workshop programs.
- Mike Dempsey, chair of the NAWCC Education Committee, instructor in
the NAWCC Field Suitcase Workshop course and instructor of Clock and
Watch Repair at Milwaukee Area Technical College.
- N. H. N. Mody, Japanese Clocks (Charles E. Tuttle Company,
Inc., first edition, 1932, and first Tuttle edition, 1967).
- Drummond Robertson, The Evolution of Clockwork (London: S.R.
Publishers Limited, 1972).
- Ernest L. Edwards, Weight-Driven Dutch Clocks and Their Japanese
Connections (Mayfield, UK: Mayfield Books, 1996).
Craig White is a mechanical engineer who graduated from Marquette
University in 1979. He now works at Ladish Co. Inc. in design engineering.
Ladish is a large forge shop specializing in forgings for the aerospace
industry.
Craig grew up in a home full of antiques and antique clocks. After the
death of his parents and subsequent inheritance of part of their collection,
his interest in clocks increased. However, his clocks needed work and having
them repaired would have been quite expensive and would have taken funds
away from acquiring more clocks! So he enrolled in a horology class at
Milwaukee Technical School. He attended classes for seven years and has
learned to do his own restoration work. Participating in four Field Suitcase
Workshops offered by the NAWCC has also supported his education. He enjoys
learning about clocks through many sources and finds that his desire to
learn increases as he learns more. |
