What did scientists contribute?

This lesson asks you to describe what scientists contributed to the fields of physics you study. The curriculum asks for Canadian scientists among others. The museum offers scholars of the Islamic world and the instruments they described, so your class will add the Canadians. ¹

Look at the expectation: it asks what scientists contributed. Ask whether a contribution is a new idea, a new instrument or a refinement of one that existed, and how a source lets you tell them apart.

Look at the balance of wisdom as a measuring instrument. Robert Hall describes a long beam, a sensitive indicator tongue and five pans used in different arrangements, including one in which the object is immersed in a known liquid ². He specifies a beam four cubits long, approximately two metres in his conversion, and an indicator around half a metre long ². He reports al-Khazini's claimed sensitivity of one part in 60,000 to one in 100,000 for a load around 4.5 kilograms, the range depending on a historical unit's value ². Sensitivity also depends on suspension, careful construction and the long tongue, not merely the number of pans ².

The records preserve no sentence in which al-Khazini or al-Biruni says why the instrument was made. For al-Khazini they show a frame stated in his own book: its preface brings knowledge, action and justice together, placing reliable measurement within a wider conception of fairness ³. Hall reads the name of the balance in both technical and ethical senses: sound discrimination of genuine and adulterated materials, alongside a well-founded and carefully constructed instrument ⁴. For al-Biruni's vessel they preserve no such statement.

Figures printed beside a device are easy to give to the wrong man. The transmitted illustration names Abu Rayhan's conical instrument ⁵. After the description, page 55 of Khanikoff's publication discusses "our author" experimenting with it, and in this publication that means al-Khazini ⁶. His repeated trials and the following table must not automatically become al-Biruni's own observations ⁶.

Ansari says the Beirut manuscript of al-Biruni's treatise and Cheikho's communication were unavailable to him, so this part of his preliminary study relies on Wiedemann ⁷. For the balance, the illustrated witness is Penn's manuscript LJS386, which Penn describes as an undated copy probably made between the later thirteenth and earlier fourteenth centuries, expressed as 1250?–1350? ⁸. The date 515/1121–1122 belongs to the treatise, not to the later manuscript pictured ^{4 8}. Ask how many hands stand between each figure and the man it is credited to.

Hall classes al-Khazini's work as an improvement, and credits al-Asfizari with the earlier movable pans ⁹. Does a refinement of an inherited instrument count as the kind of contribution your curriculum asks you to describe, and what is the strongest objection to your answer?

• The balance of wisdom: the beam, the pans and the claim about sensitivity, with Hall's account of who added what.
• Al-Biruni's displacement vessel: the conical vessel, and why the drops in its tube matter.
• Al-Khazini: the author of the treatise and the questions about his identity.
• Al-Biruni: the scholar to whom the vessel is attributed.

Read the records of al-Khazini's balance and al-Biruni's displacement vessel. For each, write one sentence on what was contributed and one on what the record says it was not.