Aḥmad ibn Mūsā (b. 803 – d. 878, Baghdad) was a Muslim Persian scholar, one of the pioneers of systems engineering and cybernetics, who also produced works in the fields of mathematics and astronomy.
His father was Mūsā ibn Shākir. From childhood he engaged in science and was especially interested in the science of mechanics. The fact that his brothers and father were scholars, that he spent his time learning science, and that he was protected by the caliph al-Ma'mun raised him even higher in the field of science and made him one of the great mathematics and astronomy scholars of his era.
He took lessons from Yaḥyā ibn Abī Manṣūr, the astronomer of the caliph al-Ma'mun. Together with his brothers Muḥammad and Ḥasan, he studied the stars and other celestial bodies and their risings and settings, and as a result of these studies he made a device that showed the rising and setting of the stars as well as their images, and he placed this device — which astonished those who saw it — in front of the Samarra Observatory. Ibn Ḥibbān al-Ṭabarī, who saw this device, could not conceal his astonishment. This device was made of copper, worked by the power of water, and could show the image and name of the stars in detail without anyone's intervention.
Alongside the science of astronomy, Aḥmad ibn Mūsā was especially interested in the science of mechanics and made hundreds of instruments large and small; among these instruments he designed automatic water containers, lamps, instruments measuring relative weight, and instruments we still use today. In the technical field neither his brothers nor any other scholar could match him.
Aḥmad ibn Mūsā, together with his brothers, was commissioned by the caliph al-Ma'mun to check whether Thabit ibn Qurra had correctly measured the circumference of the Earth. As a result of the measurements and calculations the three brothers made in Sinjar and in Kufa, they arrived at the same figure that Thabit ibn Qurra had found.
Through his work in both mechanics and astronomy, Aḥmad ibn Mūsā showed himself to be one of the greatest scholars of his era, and by producing very valuable works in mechanics he served as a pioneer for many later scholars, such as al-Jazari.
Aḥmad ibn Mūsā died in 878.
His work
The Banū Mūsā had a view of area and volume different from that of the Greeks. In the research they translated, the Greeks approached such measurements in terms of ratios rather than giving a true numerical value to volume and area. Most of them based such measurements on the relative size of another object. In one of their surviving publications, Kitāb Maʿrifat Masāḥat al-Ashkāl (The Book of the Measurement of Plane and Spherical Figures), the Banū Mūsā gave numerical values for volume and area. This is proof that they did not merely translate and reproduce the Greek sources. In fact they were building upon the concepts and setting forth some of their own original work.
They are known for inventing the first music sequencer, the earliest type of programmable machine.
Among their publications, the most popular was Kitāb al-Ḥiyal (The Book of Ingenious Devices), a book full of a hundred mechanical devices, mostly the work of the middle brother Aḥmad. The book contained some genuinely practical inventions, including a lamp that mechanically dimmed, changing fountains, and a hooded scoop. Eighty of these devices were described as "trick vessels" that showed real mechanical mastery with a genuine focus on the use of slight pressure. Some of the devices appear to be copies of earlier Greek works, but the rest were far more advanced than anything the Greeks had made.
They made many observations and contributions to the field of astronomy, writing about a dozen publications on their astronomical research. They made many observations concerning the Sun and Moon. Al-Ma'mun took them into a desert in Mesopotamia to measure the length of a degree. They also measured the length of a year as 365 days and 6 hours.[1]
Instruments he used
Lamps that did not go out in the wind, whose wick automatically emerged as it burned, and which fed in fresh oil as the oil was consumed.
Water troughs for livestock that filled automatically as the animals drank water.
A garden irrigation system: an automatic system that sounded a whistle to give notice when the irrigation was finished.
Vessels that measured relative weight.
His works
Kitāb al-Ḥiyal (written in the fields of systems engineering and mechanics.)
The geometric proof that there is no ninth sphere outside the sphere of the fixed stars.
Sources
- Turkish Wikipedia: tr.wikipedia.org
- TDV Encyclopedia of Islam: islamansiklopedisi.org.tr
- English Wikipedia: en.wikipedia.org