144 SCENERY OF THE HEAVENS. 



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 trans- Atlantic 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 totter on 

 its base, and the astronomer himself only survive in the gratitude of his posterity ; but 

 the record remains, and tranfuses all its own exactness into every determination which 

 takes it for a groundwork, giving to inferior instruments, nay, even to temporary contri- 

 vances, and to the observations of a few weeks or days, all the precision attained origin- 

 ally at the cost of so much time, labour, and expense." 



In the earliest times of which we have any account, mankind appear to have been 

 acquainted with the use of the stars as celestial guideposts in their travels by land and 

 voyages on the deep. We may conclude their observance in the former circumstances to 

 have had the precedence. Without being aware of some safe and sure method of directing 

 their course by night, acquired in journeys on shore, men would hardly venture upon a 

 night voyage at sea. It is likely that in the great Oriental deserts, those immense plains 

 with few natural landmarks, the useful discovery was made how accurately the traveller 

 may direct his footsteps by a cultivated acquaintance with the stars, which stimulated 

 enterprize upon the pathless waters, and laid the foundations of maritime expeditions. 

 Diodorus Siculus expressly states that travellers in the sandy deserts of Arabia were 

 accustomed to direct their course by the Bears, the two constellations of that name, a fact 

 which the Koran recognises in the passage: " God has given you the stars to be guides in 

 the dark both by land and sea." The honour of inventing nautical astronomy is usually 

 assigned to the Phenicians, but some knowledge of it prevailed among the Greeks as early 

 as the time of the Trojan war. Ulysses is represented sailing on his raft, sitting at the 

 helm, and watching the stars through the night. "While, however, the Greek sailors chiefly 

 confined their observations to Ursa Major, the Phenician navigators made a closer 

 approximation to the north. Aratus tells us, referring to Ursa Minor : 



" Observing this, Phenicians plough the main." 



The renowned pilot of the Trojan fleet, Palinurus, through intently watching the face of 

 the nocturnal heavens at the helm, fell overboard, and for a time was lost to his com- 

 panions. The Pleiades are supposed to derive their name from TrXeetv, to sail, because, 

 during the winter months, they were of high importance to the benighted Greek mariner. 

 It must appear marvellous in the extreme to the uninformed, that now the skilful navi- 

 gator, on a before un visited ocean, can determine positively where he is, to within five 

 miles, by means of the stars ; and ascertain his distance from, and true course to, any known 

 meridian or harbour of the globe. From the deck of his ship he has merely to measure 

 the moon's apparent distance from certain stars, to compare the result with their true 

 places as given in the Nautical Almanack for every day in the year, and he finds his lon- 

 gitude. There are nine conspicuous stars which are chiefly used for this purpose, owing 

 to their position being contiguous to the moon's path in the heavens; a Arietis, Alde- 

 baran, Pollux, Regulus, Spica Virginis, Antares, Altair, Fomalhaut, and Markab. The 

 late Captain Basil Hall on one occasion was at sea for eighty-nine days, passing in the 

 interval through a distance of eight thousand miles, without once making land or seeing 

 a single sail on the voyage, but with unerring precision he came direct to his destination. 

 His course lay from San Bias on the west coast of Mexico, through the Pacific Ocean, 



