Al-Hiyal, written by the Banu Musa brothers (Muhammad, Hasan, and Ahmad), is regarded as the earliest known text on mechanics in the Islamic world, dating back to around 236 AH. Among the three brothers, Ahmad ibn Musa emerged as the leading mind in mechanics. His work meticulously details and illustrates various self-operating devices and mechanisms, primarily driven by the mechanical properties of fluids. This landmark book presents one hundred devices, including water cycles, irrigation pumps, and self-refilling containers, along with other ingenious tools that continue to intrigue readers.

The book is divided into two main sections: weightlifting mechanisms and mobile devices, both founded on principles of statics. Many of these inventions, such as the sound alert system and dredging device, demonstrate the advanced scientific understanding of mechanics in the Islamic Golden Age. The manuscript includes illustrations and alphabetic annotations, facilitating the reader’s engagement with each device.

The influence of earlier inventors, such as Philo and Heron, is clearly visible, with Donald Hill noting detailed comparisons between their works. Complete copies of Al-Hiyal are housed in the libraries of Topkapi Palace in Istanbul, the Vatican, and Germany, with the current edition based on a 607 AH manuscript in the Berlin Library (catalog no. 739).