Astrolabe Catalogue

 

Date early 18th century
Maker ‘Abd al-A’imma
Place Iṣfahān
Material Brass
Inventory no. 40833
Acquisition Presented by J. A. Billmeir in 1957

Rule, Regula, Pointer and Alidade Images

Alidade Image:

astrolabe part (photo)

Rule Image:

astrolabe part (photo)

Rule

Appearance Tip Sights Pinholes Notches Description
Double-ended,  counter-changed,  original.  Simple None None None It is possible that this rule is a replacement. Islamic astrolabe rarely have a rule or pointer on the front of the instrument. Moreover, the silver knob at the bottom of the rete prevents this rule from rotating around the entire circle.

Scales


Type Range & Units Numbered Geometry Location
Declination 0 - 90 Degrees Every 6 degrees Linear Rule, left arm
Equal hours 0 - 24 Times of day Every 1 hours Linear Rule, right arm

Alidade

Appearance Tip Sights Pinholes Notches Description
Double-ended,  original.  Simple Rigid Double None

Scales


Type Range & Units Numbered Geometry Location
Sine/Cosine 0 - 60 1/60 of quadrant radius Every 5  Linear Rule, right arm
Unequal hours 1 - 12 1/12 of daylight Every 1 hours Linear Rule, right arm
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