Ibn Muadh's treatise on twilight

Ibn Muadh's eleventh-century twilight treatise connects first light with atmospheric height. The Arabic label here is descriptive:Smith discusses a proposed title reconstruction from Arabic terms transliterated in Latin,not an original the museum found. The work is known in Latin transmission asLiber de crepusculis ³.

The height-method entry distinguishes the historical result around52miles from simpler modern museum teaching. Calvo gives18degrees,solar distance1110Earth radii,linear size ratio5.5:1and circumference24000miles. We do not turn these into modern atmospheric measurements or copy a decimal error in another web example to force agreement ^{1 4}.

Smith reports technical analysis concentrated on dawn on the basis of an overall similarity between morning and evening,with a reported colour distinction:whiteness predominating in the former,redness in the latter. This describes his note,not a new observing experiment or proof of identical viewing conditions ⁵.

The Arabic original is not known extant. Smith's abstract lists one Hebrew,25Latin and one Italian witness,and comparison of22Latin texts for the critical edition. His notes identifyParis,MS Hebr.1036for Samuel ben Jehuda's Hebrew translation. These are scholarly reports,not manuscripts we examined or images we republish ^{6 7}.

TDV and Smith explain Sabra's correction of the old Ibn al-Haytham attribution. Some copies being bound with the optics helps explain possible confusion;Abhomadiname forms support the actual author's identification. Binding order is not an accusation of forgery,and each Latin title is not a new Arabic work ^{8 9}.

The figure remained standard in Latin reception before revision involving refraction and barometric studies. Popularity does not validate a sharply bounded atmospheric model. Calvo,TDV and Smith's public abstract/visible notes were read here—not the whole critical edition,manuscripts or Sabra's independent paper ^{10 2}.