'If we ask to what end magnificent establishments are maintained by States and sovereigns, furnished with masterpieces of art, and placed under the direction of men of first-rate talent and high-minded enthusiasm, sought out for those qualities among the foremost in the ranks of science, if we demand, cui bono? for what good a Bradley has toiled, or a Maskelyne or a Piazzi has worn out his venerable age in watching?—the answer is, Not to settle mere speculative points in the doctrine of the universe; not to cater for the pride of man by refined inquiries into the remoter mysteries of nature; not to trace the path of our system through space, or its history through past and future eternities. These, indeed, are noble ends, and which I am far from any thought of depreciating; the mind swells in their contemplation, and attains in their pursuit an expansion and a hardihood which fit it for the boldest enterprise. But the direct practical utility of such labours is fully worthy of their speculative grandeur. The stars are the landmarks of the universe; and, amidst the endless and complicated fluctuations of our system, seem placed by its Creator as guides and records, not merely to elevate our minds by the contemplation of what is vast, but to teach us to direct our actions by reference to what is immutable in His works. It is, indeed, hardly possible to over-appreciate their value in this point of view. Every well-determined star, from the moment its place is registered, becomes to the astronomer, the geographer, the navigator, the surveyor, a point of departure which can never deceive or fail him, the same for ever and in all places; of a delicacy so extreme as to be a test for every instrument yet invented by man, yet equally adapted for the most ordinary purposes; as available for regulating a town clock as for conducting a navy to the Indies; as effective for mapping down the intricacies of a petty barony as for adjusting the boundaries of Transatlantic empires. When once its place has been thoroughly ascertained and carefully recorded, the brazen circle with which that useful work was done may moulder, the marble pillar may totter on its base, and the astronomer himself survive only in the gratitude of posterity; but the record remains, and transfuses all its own exactness into every determination which takes it for a groundwork, giving to inferior instruments—nay, even to temporary contrivances, and to the observations of a few weeks or days—all the precision attained originally at the cost of so much time, labour, and expense.'
But for these strictly utilitarian purposes a comparatively small number of stars would meet our every requisite. In the narrow sense of which Sir John Herschel is here speaking, we have no use for anything beyond the smallest of catalogues; and if the question before us is, 'Why are we continually extending our catalogues?' the following words of a more recent writer[4] on the subject will set forth the real explanation:—
'A word in conclusion, suggested by the history of star-catalogues. We have no difficulty in understanding that it is necessary to study the planets, and a reasonable number of the brighter stars, for the purpose of determining the figure of the earth, and the positions of points upon its surface; but the use for a catalogue of ten thousand stars, such as La Caille compiled, is not just so apparent. Nay, what did Ptolemy want with a thousand stars, or Tamerlane's grandson, born, reared, and destined to die amidst a horde of savages, however splendid in their trappings? There is not, and there never was, any real, practical use for the great volumes of star-catalogues that weigh down the shelves of our libraries. The navigator and explorer need never see them at all. Why, then, were these pages compiled? Why have astronomers, from Hipparchus's time to the present, spent their lives in the weary routine-work of observing the places of tiny points in the stellar depths? Does it not seem that there is something in the mind of man that impels him to seek after knowledge—truly—for its own sake? something heaven-born, heaven-nurtured, God-given ... that there is something in man common to him and his Creator, and therefore eternal ... in beautiful accord with the plain statement that "God made man in His own image?"'
CHAPTER VIII
THE ALTAZIMUTH DEPARTMENT
The determining of the places of the fixed stars which Flamsteed carried out so efficiently in his British Catalogue of Stars—the first 'Census of the Sky' made with the aid of a telescope—was but half of the work imposed upon him. The other half, equally necessary for the solution of the problem of the longitude at sea, was the 'Rectifying the Tables of the Motions of the Heavens.'
This second duty was not less necessary than the other, for, if we may again use the old simile of the clock-face, the fixed stars may be taken to represent the figures on the vast dial of the sky, whilst the moon, as it moves amongst them, corresponds to the moving hand of the timepiece. To know the places of the stars, then, without being able to predict the place of the moon, would be much like having a clock without its hands. But if not less necessary, it was certainly more difficult. The secret of the movements of the moon and planets had not then been grasped, and the only tables which had been calculated were based upon observations made before the days of telescopes.