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some suitably selected star, recorded in tables, suffices, bycomparison with the local time at which it is seen to be at thesame distance from the star, to enable the mariner, who, farout of sight of land, is cleaving his way across the pathlessdeep, to determine his longitude with an accuracy which is ofmuch importance, notwithstanding that modern chronometershave been so greatly improved that, independently of lunarobservations, they afford a still closer approximation to itstrue value.
A due appreciation of the Moon should therefore in nowise be wanting in a country whose maritime and manu-facturing interests are so important as those of England, oramongst the merchant princes of the city of London . It was,we think, very consistent with the distinguished positionwhich Sir Thomas Gresham held in our great metropolis,that in the foundation which he appointed by his will hedirected that the Reader in Astronomy should pay specialattention to the nautical branch of the science. Since his day,however, the confines of astronomical study have immenselywidened, and nautical astronomy has been so much reducedto a series of routine calculations, by means of formulas andtables, that it is hardly possible, in a lecture such as thepresent, duly to explain what is more fitted for a class ofstudents in navigation. Still it must not be forgotten that ifauy improvement is to be effected in the accuracy of ourknowledge of the Moon ’s position, or in the methods by whichthat knowledge may be practically utilized, it must be by adue encouragement of suitable observations, and of the pro-gress of astronomical science in general.
There was formerly a small observatory erected by theGresham Committee (having the star <y Draconis nearly in itszenith) in old Gresham College , which in its day was veryuseful, and in which Dr. Hooke appears, without knowing themeaning of his discovery, to have effected the first detection ofthe aberration of light. We now rejoice in the existence, notonly of the great national observatory at Greenwich, and ofthose connected with the universities of Oxford and Cam-bridge, but of several of comparatively small size, founded