The apparition of the great comet of 1843 gave an additional fillip to the movement. To the excitement caused by it the Harvard College Observatory--called the "American Pulkowa"--directly owed its origin; and the example was not ineffective elsewhere. The United States Naval Observatory was built in 1844, Lieutenant Maury being its first Director. Corporations, universities, municipalities, vied with each other in the creation of such institutions; private subscriptions poured in; emissaries were sent to Europe to purchase instruments and to procure instruction in their use. In a few years the young Republic was, in point of astronomical efficiency, at least on a level with countries where the science had been fostered since the dawn of civilisation. A vast widening of the scope of astronomy has accompanied, and in part occasioned, the great extension of its area of cultivation which our age has witnessed. In the last century its purview was a comparatively narrow one. Problems lying beyond the range of the solar system were almost unheeded, because they seemed inscrutable. Herschel first showed the sidereal universe as accessible to investigation, and thereby offered to science new worlds--majestic, manifold, "infinitely infinite" to our apprehension in number, variety, and extent--for future conquest. Their gradual appropriation has absorbed, and will long continue to absorb, the powers which it has served to develop. But this is not the only direction in which astronomy has enlarged, or rather has levelled, its boundaries. The unification of the physical sciences is perhaps the greatest intellectual feat of recent times. The process has included astronomy; so that, like Bacon, she may now be said to have "taken all knowledge" (of that kind) "for her province." In return, she proffers potent aid for its increase. Every comet that approaches the sun is the scene of experiments in the electrical illumination of rarefied matter, performed on a huge scale for our benefit. The sun, stars, and nebulæ form so many celestial laboratories, where the nature and mutual relations of the chemical "elements" may be tried by more stringent tests than sublunary conditions afford. The laws of terrestrial magnetism can be completely investigated only with the aid of a concurrent study of the face of the sun. The solar spectrum will perhaps one day, by its recurrent modifications, tell us something of impending droughts, famines, and cyclones.