The Astronomical Observatories of Jai Singh c15.s3: European Astronomy
The Astronomical Observatories of Jai Singh c15.s3
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European Astronomy
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76. In Europe, after the death of Ptolemy in the second century of our era, very little advance was made for a thousand years. The Christian church often opposed scientific enlightenment, and sometimes persecuted those who sought it; and the patristic writings contain the grossest of astronomical absurdities.
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But, about the thirteenth century, sounder opinions began to prevail, and in the early part of the sixteenth century Copernicus wrote his *De Revolutionibus Orbium Cœlestium*. Tycho Brahe, Kepler, and Galilei preceded Jai Singh by about a century. Greenwich observatory was founded some forty years before that at Delhi. Newton's *Principia* was written at the time of Jai Singh's birth; Huygens died a few years later; Flamsteed's catalogue of stars was first printed in 1688; Halley, in 1705, predicted the return of the comet named after him; the aberration of light was discovered in 1727. Jai Singh succeeded to the Amber territory in 1699, and the Delhi observatory was built about 1724.
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77. The European instruments, at the beginning of the seventeenth century, were, in principle, much the same as those used by the Greeks and Arabs. Tycho Brahe³ (1546-1601) had several sextants and quadrants, a parallacticum (see p. 82), and armillary circles; Hevelius (1611-1687) had a somewhat smaller battery of similar instruments; and Flamsteed (1646-1720) used a quadrant of 3 feet and a sextant of 6 feet radius.
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³ See DREYER'S *Tycho Brahe*, xii, 315 ff.
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The telescope was used for the general observation of heavenly bodies in 1609 by Galilei, and telescopic sights were first systematically used about A.D. 1667. Gascoigne was probably the first (circa A.D. 1640) to introduce these, and he also invented a micrometer. Some twenty years later, Huygens devised, independently, the same contrivance. Hevelius introduced the vernier and tangent screw; Flamsteed used cross wires in the eye pieces of his sighters; Galilei had used a pendulum for short time measurements; Huygens devised a pendulum clock (1656), and Jean Picard (1620-1682) introduced regular time observations at the new observatory at Paris.¹ J. D. Cassini (1625-1712), it is stated, devised schemes (never realised) for the construction of gigantic instruments.²
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¹ An excellent, although all too brief, account of European instruments is given in the *History of Astronomy* by G. Forbes, while Dreyer's *Tycho Brahe* is the only adequate account of mediæval astronomy (and instruments) in the English language.
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² A. Berry—*A Short History of Astronomy*, p. 160.
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78. The Hindus, Arabs and Europeans all derived the fundamentals of their astronomical science from the Greeks. It was the Hindus who first profited by Greek experience, then the Arabs and lastly the Europeans. The last, indeed, obtained their knowledge of Greek astronomy primarily through the Arabs.
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The following chronological scheme exhibits fairly well the relationship between the three schools:—
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GREEK Astronomy. PTOLEMY 2nd Cent. A.D. HINDU 5th Cent. ARAB 9th Cent. EUROPEAN 14th Cent. Mahendra, etc. JAI SINGH 1686-1743.
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When we examine carefully the methods of the several schools we find somewhat marked differences. Even among the Greek astronomers (e.g., Ptolemy himself) there was a distinct tendency to work on the observations recorded by their predecessors, and, in the later Greek schools, there was a consequent neglect of observational astronomy. With the Hindus this tendency was emphasised to a remarkable extent, and practical work was neglected almost completely. The instruments they describe are either for purposes of, what may be termed, theoretical calculations, or for purposes of demonstration (see page 78). They built no observatories and they made no systematic records of observations.
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The Arabs and other Muslim astronomers took an entirely different line. They recognised the value of practical observation; but they hardly suspected the need for a re-examination of the Greek theories. They built observatories and devised improvements in the instruments, and set about verifying and correcting Ptolemy's elements.
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The European astronomers were, perhaps, not quite so bound by tradition as were the Hindus and the Arabs. The death of the Ptolemaic theory and the invention of the telescope gave a great impetus to research, and the European astronomers largely discarded the methods of their predecessors. They recognised the inevitability of observational error, and devised means to counteract it; they were forced to consider, as of great importance, facility of observation, and gradually they devised instruments of types, unimaginable to their Arabic teachers.