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{{Item
 
{{Item
 
| name  = Barometer
 
| name  = Barometer
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A '''barometer''' is a device that gauges atmospheric pressure.  It is used in Egypt to measure the altitude at the holder's location.  Knowing your altitude is crucial to properly mixing a [[Test of the Ritual Tattoo|Ritual Tattoo]], and is also helpful in planning [[Aqueduct]] routes.
 
A '''barometer''' is a device that gauges atmospheric pressure.  It is used in Egypt to measure the altitude at the holder's location.  Knowing your altitude is crucial to properly mixing a [[Test of the Ritual Tattoo|Ritual Tattoo]], and is also helpful in planning [[Aqueduct]] routes.
  
==Source==
+
==Sources==
  
 
Made in a [[Glory Hole]].
 
Made in a [[Glory Hole]].
Menu options: Start Making > Special Projects> add spheres from the highest quality to lowest.
+
Menu options: Start Making > Special Projects (add spheres from the highest quality to lowest).
  
 
This item becomes available once you have begun the [[Test of the Ritual Tattoo]].
 
This item becomes available once you have begun the [[Test of the Ritual Tattoo]].
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The reported reading is the true altitude, plus or minus an error that follows a sine wave over the course of the game day:
 
The reported reading is the true altitude, plus or minus an error that follows a sine wave over the course of the game day:
  
   t = (egypt minutes since midnight) / (24*60)
+
   t = (Egypt minutes since midnight) / (24*60)
 
   reported altitude = true altitude + E * sin(2*pi*t)
 
   reported altitude = true altitude + E * sin(2*pi*t)
  

Latest revision as of 15:09, 13 May 2021

Barometer
Barometer
(Item)
Weight 1
Bulk 1


A barometer is a device that gauges atmospheric pressure. It is used in Egypt to measure the altitude at the holder's location. Knowing your altitude is crucial to properly mixing a Ritual Tattoo, and is also helpful in planning Aqueduct routes.

Sources

Made in a Glory Hole. Menu options: Start Making > Special Projects (add spheres from the highest quality to lowest).

This item becomes available once you have begun the Test of the Ritual Tattoo.

Cost

Notes

Barometers, like other crafted tools, have a quality associated with them. A higher quality barometer is more accurate.

Final quality of a Barometer can be determined by doing the following formulas: Average = FLOOR((A + B + C) / 3).
Final quality = Average - ABS(Average - A) - ABS(Average - B) - ABS(Average - C)
Where A, B and C are the quality of the Barometric Spheres

Use

When carried, a new menu option becomes available under Special > Measure Altitude. This immediately reports the altitude of your current location in Main, in feet and inches.

Typical altitudes are 0 (sea level) - 600 feet (top of a tall 'mountain')

Research and Tuition

Accuracy

Data for a quality 1940 barometer

As in previous tales, barometers appear to report an altitude that varies according to the in-game time of day and the quality of the barometer.

The reported reading is the true altitude, plus or minus an error that follows a sine wave over the course of the game day:

 t = (Egypt minutes since midnight) / (24*60)
 reported altitude = true altitude + E * sin(2*pi*t)

E is the maximum error of the barometer, which depends in some (currently unknown) way on the barometer's quality. E is smaller for higher quality barometers.

All barometers are perfectly accurate at 12AM and 12PM gametime (sin(0) = sin(pi) = 0), and are most inaccurate at 6AM (too high by E inches) and 6PM (too low by E inches).

Determining E

You can find E for a given barometer by measuring the altitude of exactly the same spot at 6AM gametime, then again at 6PM gametime. Convert the readings to inches, then:

 E = ((reading at 6AM) - (reading at 6PM)) / 2

It's best to use a flat area with an obvious marker to stand at, so that you can be sure you're measuring at the same spot each time.

Make sure your test spot is at least 10 feet above sea level, you don't want either reading to be 0.

Quality vs E

Quality 6AM reading 6PM reading E (inches) Notes
1 ? ? 60 from the T2 wiki
1940 41' 10" (502 inches) 33' 0" (396 inches) 53 T4 verified
3734 73' 0" (864 inches) 65' 1" (781 inches) 47.5 T4 verified
6517 72' 0" (864 inches) 66' 1" (793 inches) 35.5 T4 verified
8007 71' 3" (855 inches) 66' 10" (802 inches) 26.5 T4 verified