"To accomplish the exalted command which he had received, he (Jeysing) bound the girdle of resolution about the loins of his soul, and constructed here (at Delhi) several of the instruments of an observatory, such as had been erected at Samarcand, agreeably to the Musalman books: such as Zat-ul-huluck, of brass, in diameter three guz of the measure now in use (which is nearly equal to two cubits of the Koran), and Zat-ul-shobetein, and Zat-ul-suchetein, and Suds-Fukheri, and Shamlah. But finding that brass instruments did not come up to the ideas that he had formed of accuracy, because of the smallness of their size, the want of division into minutes, the shaking and wearing of their axes, the displacement of the centres of the circles, and the shifting of the planes of the instruments; he concluded that the reason why the determinations of the ancients, such as Hipparchus and Ptolemy, proved inaccurate, must have been of this kind; therefore he constructed in Dar-ul-kheláfet Shah-Jehanabad, which is the seat of empire and prosperity, instruments of his own invention, such as Jey-per-gàs and Ram-junter, and Semrat-junter, the semi-diameter of which is eighteen cubits, and one minute on it is a barleycorn and a half, of stone and lime, of perfect stability, with attention to the rules of geometry and adjustment to the meridian, and to the latitude of the place, and with care in the measuring and fixing of them; so that the inaccuracies from the shaking of the circles, and the wearing of their axes, and displacement of their centres, and the inequality of the minutes, might be corrected.
"Thus an accurate method of constructing an observatory was established; and the difference which had existed between the computed and observed places of the fixed stars and planets, by means of observing their mean motions and aberrations with such instruments, was removed. And, in order to confirm the truth of these observations, he constructed instruments of the same kind in Sewaī Jeypoor, and Matra, and Benares, and Oujein."
After this most interesting visit to the Observatory, we returned to Delhi.
