Hello
Can someone Identify this Japanese navy calculating instrument. Any help will greatly appreciated. Thanks in advance.
Can someone Identify this Japanese navy calculating instrument. Any help will greatly appreciated. Thanks in advance.
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japanese Navy calculating instrument
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japanese Navy calculating instrument
one more picComment
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天測計算尺
Tensoku keisanjaku
Astronomical observation
Celestial slide rule
天測 【てんそく】 (n) astronomical observation; shooting the sun
計算尺 【けいさんじゃく】 (n) slide rule
When I searched the kanji I happened upon this site. I did a search for 天測計算尺 but only got hits for the first two kanji, Tensoku. Each of these three hits had to do with calculating the sun's position on the horizon: a transit, a sextant, and a chronometer. But none of these has that rotating cylinder.
Hmmmmmm.....
I wonder if it fit in a housing like this "Hand-Cranked Calculator" found on the same page:
--GuyComment
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japanese Navy calculating instrument
I was told it was something to do with Japanese torpedo's. I added a few more pics it extends out top and bottom. Maybe someone can come up with an answer. Would never work in a calculating machine it's three pieces.
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japanese Navy calculating instrument
couple more picsComment
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naval flight navigational calculation devise
I would like to share with all what this device actually is. The piece is a naval flight navigational calculation devise used in aircraft…its called a positional line slide rule. The army generally used different devises. By WWII it continued in use but was becoming somewhat obsolete and replaced by other better instruments. In the field some remained in use due to no better equipment. If you have the book aviator uniforms and equipment of IJN it's on page 123. Too bad it's in Japanese maybe someone can shed more light on the subject.Comment
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You MIGHT have 1 of 4 known Japanese Bygraves
[EDIT: The Slide Rule Museum paper (2008) states there are three known Japanese-version Bygrave slide rules known to exist.] You might want to contact Ronald van Riet. I found his contact info on a translator website ronald@van-riet.nl.
Thanks for informing us of your successful research.Originally posted by Bekora View Post
The text is too complicated for me to attemp. I did find this:
Wiki article hereBygrave Position-Line Slide Rule. Celestial navigation requires complicated computations. Performing these calculations in cramped open cockpits with low temperatures and wind speeds of over 160 kilometers (100 miles) per hour was part of what made navigation difficult in the early years of aviation. Thankfully, Capt. L. C. Bygrave developed this handy slide rule shortly after World War I. It provided the best shortcut method of speeding up celestial computations at the time.
source
another using same image posted below.
One was sold on Ebay $515.05. linkCylindrical slide rules even existed. There were two types of slide rules: ones on a helical scale and ones on a bar scale. The advantage of the cylindrical slide rule were that much longer scales could fit on it, allowing for greater precision than circular or linear ones.
source
Finally ... here's a Slide Rule Museum paper that also addresses the Japanese Bygrave [the Ebay description was culled from this paper]."Japanese version of the Bygrave
A Japanese version of the standard Bygrave Mk. II was built. It
has the same dimensions, the same original cursor design and all
text seems to be a straightforward translation of the English
version. Figure 20 shows the example from a German collector who
wishes to remain anonymous, while [Hems 2004] shows pictures
of a Japanese Bygrave coming from an American collector {JB},
identical in lay-out, as is a third Japanese Bygrave known to
exist. Differences in small imperfections between these three
prove that they do not depict the same sample, so at least three of
the Japanese Bygraves have survived. Attempts to contact the
owners of two of these three Japanese examples have been
unsuccessful so far.
This Japanese Bygrave does not show any designation or
manufacturer, the only markings on the top of the slide rule
are “NO. 872” (which looks to be a serial number)and the Japanese Katakana character "垉” in a circle with an
anchor sign, which when used in combination was a stamp of
acceptance by the Japanese naval forces. This does not
necessarily mean that the Japanese used them on board ships:
both before and during World War II the Japanese navy had a
sizeable air fleet, as large as or even larger than that of the
Japanese army (there was no separate Japanese air force).
Whether 872 is a serial number in the same series as those of the
regular Bygraves, is not known.
Again, no production details are known, and nothing is known of
its history: why the Japanese ordered these, how many were
built, if they were actually ever delivered to Japan or used in
actual service."
Cheers!
--GuyComment
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I have recently been told about this thread on this interesting slide rule. People who want to contact me directly can use my private email address ronald@van-riet.nl
I have written an extensive paper on this kind of slide rules, please go to https://sites.google.com/site/slider...ne-slide-rules where you can download this paper and a few others on slide rules used in aviation. I would like to include this particular one with the name of the owner in a future update of this paper, but will not include names without explicit permission.
I consider it possible that this is one of the Japanese Bygraves that I have referred to in my paper as the serial number unknown, but I would have to know more about its history before I can positively do that.
The serial number of the Japanese Bygrave that started this discussion is very high and I was surprised to see a number that high, suggesting that more than 1450 of these instruments were built for or in Japan.
I will definitely keep an eye on this thread for more interesting information and if someone has a link to the book (in Japanese) that shows this particular instrument, I would be grateful...
Ronald van RietComment
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