Concise 480

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Concise No. 480 Professional

Obverse. In this example, the perpetual calendar sets 'E' against the common January for 2006. Coincidentally, the inner index is set against April 1st. The hairline is set on January 22nd and indicates that April 1st is 69 days away.

Reverse

1 Calendar computing features
2 Calculating Features
3 References

Type: Circular
Size: 4 Inches / 10 cm
Material: Plastic
Scales:
- Front:
  - Elapsed Years
  - Day of Year
  - Elapsed Days
  - Elapsed Weeks + Days Past,
  - Japanese Regnal Year + Calendar Index + Common Era Year
  - Perpetual Calendar in center with windows for Day of Week and Calendar Index
- Back: A D / C CI B K L
HvH: 5645

Front and rear disks slide independently. Slide circles set flush to body. With vinyl case and instruction sheet in Japanese.

[edit] Calendar computing features

Weekdays (曜日)
日	nichiyōbi	Sun	Sunday
月	getsuyōbi	Moon	Monday
火	kayōbi	Fire	Tuesday
水	suiyōbi	Water	Wednesday
木	mokuyōbi	Wood	Thursday
金	kin'yōbi	Metal/Gold	Friday
土	doyōbi	Earth	Saturday

Reading from the inside to the edge:

Perpetual calendar. Settings are available for Heisei era years 15-30, plus generic indices A through G for years outside that range. Align the year number or index underneath the month number and read the weekdays in the upper window. 「閏年の 1, 2月は⾚数字に合せる」 means "Use the red numbers for January and February of leap years."

Nengō (年号)
明治	Meiji	1868
大正	Taishō	1912
昭和	Shōwa	1926
平成	Heisei	1989

年号 / 西暦: Nengō (Japanese Era) and Seireki (Western) year scales and calendar index. For the years 1905 through 2022, this scale lists the calendar index letter and the corresponding regnal year. This scale can be used against the elapsed year scale, outermost on the stator, to calculate age or years elapsed. (But, you ask, Why don't we just subtract? Well, I answer, how long is it between Shōwa 39 and Heisei 18? No way to know unless you know the epochs of the Heisei and Shōwa eras. Since many official documents are dated in this way, some sort of table or calculator is essential.)

逆日数 / 週数: Opposite Days / Weeks. The black portion of this scale can be used against the month/day scale to calculate what day it is N weeks from now. The red part of the scale is reverse-calibrated against the month/day scale to calculate how long in the past an event was. The scale is marked off in 5-day intervals, but i guess you can use the main Number of Days scale to interpolate.

日数: Number of Days. Used against the month/day scale to determine intervals and ending dates. Special indices on this scale let you account for fencepost errors (e.g. if February 7th is the first day of some period, what is the 45th day?)

Month/day scale. Gives dates in month/day format, 365 days for a common year. (The instructions just have you add one when appropriate during leap years.) Months 2, 4, 6, 9 and 11 are marked in red to remind you that "Thirty days hath September, etc."

年数(年令): Number of Years (Age). Use against the year scales to calculate intervals, ending years or personal ages.

The calendar features are intended for use with the Japanese regnal calendar, in which each emperor's accession starts a new era (nengō, 年号) and a new Year 1. The current unit has quick settings for Heisei years 15 through 30 (2003-2018, assuming His Majesty the Emperor is spared).

[edit] Calculating Features

The sliderule on the reverse is unremarkable except for the unit conversions around the outer circumference. In addition to metric and English units are several traditional Japanese units:

(Clockwise from the index)

Length
- 1 in = 2.54 cm = 0.8382 寸 (sun)
- 1 ft = 0.3048 m = 1.006 尺 (shaku)
- 1 mile = 1.609 km = 0.4098 里 (ri)
- 1 尺 (shaku) = 30.3 cm
- 1 間 (ken) = 1.818 m

Area
- 1 in² = 6.452 cm²
- 1 ft² = 0.0929 m²
- 1 acre = 0.4047 ha = 1224.12 坪 (tsubo)
- 1 坪 (tsubo) = 3.306 m²
- 1 a = 100 m²
- 1 ha = 100 a

Volume
- 1 in³ = 16.39 cm³
- 1 ft³ = 0.02832 m³
- 1 Imp. gal = 4.546 L
- 1 U.S. gal = 3.785 L = 2.0985 升 (sho)
- 1 ⽴坪 (? tsubo) = 216 尺³ (shaku³) = 6.0105 m³
- 1 升 (sho) = 1.804 L