One variety of the Quadrant is the Horary Quadrant. It enables the reading of the time that has elapsed since sunrise (during the forenoon) and that is yet to elapse before sunset (during the afternoon). In the Islamic world another variety of the Quadrant, called Sine Quadrant was developed, which also entered India. This was used mainly for trigonometrical calculations. The Nocturnal enables the reading of time during the night and is based on the diurnal rotation of the stars round the North Pole.

            The first 10 entries of this album were examined by Dr. S. R. Sarma, when he was engaged in a project for compiling a catalogue of scientific instruments preserved in different museums and repositories. He had then written a detailed note on the astrolabes and sundials at this Library. This was published in the Khuda Bakhsh Library Journal (No.118 – Dec.1999). The information provided by the eminent scholar for each of these entries has been reproduced in this album. Entry 11 (astrolabe) and Entry 12 (surgical forceps) could not be examined by him. The information for these two entries has been provided by my colleagues, Dr. Salimuddin Ahmad and Mr. Abu Muzaffar Alam. I am thankful to them. I am also thankful to Dr. Ahmad A. Hai, Hon’ble Member of the Khuda Bakhsh Library Board and a renowned surgeon, for his advice and suggestions.

            I wish to add here that this album is intended as a tribute to Khan Bahadur Khuda Bakhsh in the year of the centenary of his death.  Khuda Bakhsh was born on 2^nd of August 1842 at village Okhai near Chapra in north Bihar. He began his career as a Peshkar, rose to be an eminent public pleader and subsequently the Chief Justice (Mir Majlis) of the Nizam’s Supreme Court at Hyderabad (1895-98). His last years were spent at Patna, where he died on 3^rd of August, 1908.

Khuda Bakhsh had a passion for manuscripts. There were over 4000 manuscripts in his personal collection, including hundreds of rare ones. In fact, some of the manuscripts in his collection are the only extant copies in the world. Even when he faced major financial hardship and suffered from failing health, he refused to sell off any of the manuscripts of his collection. He dedicated the entire collection to the people of Patna, a gesture for which he was conferred the title of Khan Bahadur.