Before the building of this unique little ves sel (described as a yacht for convenience in entering port, and making arrangements with customs, etc.), the magnetic observers of the Carnegie Institution had sent its brigantine, the Galilee, on cruises amounting in the aggregate to 60,000 miles. Its magnetic observers had penetrated to nearly every part of the earth, and have been, and still are, co-operating with various polar expeditions, securing magnetic data in those regions. The result is a set of magnetic charts for the greater part of the earth at least, the first which can be said to be based upon uniformly and systematically acquired data. The good will and co-operation of every civilized country have been mani fested in this great work.
The usefulness of the Carnegie, and of the various forms of work akin to that which she has done, has practically no limitations for the simple reason that not only has the magnetic state of our globe been hitherto unascertained with certainty, but it is constantly changing.
This became known as early as 1634, when Henry Gellibrand noted that since 1584 the easterly direction of the compass had changed by seven degrees. Obviously, this affects more or less every survey that is made. Hence the work of the Carnegie Institution extend§ not only over the sea but also on land. The work by sea is, however, of far greater significance from the point of view of the security of human life, since a variation of a minute frac tion in the compass may result — as has been the case once or twice — in the wrecking of a liner on rocks supposed to have been cor rectly charted. On 8 June 1914, after refitting at New York the Carnegie left for an expedi dition in the North Atlantic. After visiting Norway, Spitzbergen in the latitude of 79° 52', and Iceland, and covering 10,600 miles, she re turned to her base station at Greenport, Long Island, 9 Oct. 1914. She refitted at Brooklyn for a longer cruise during 1915-16, in southern latitudes (50° to where magnetic obser vations required supplementing.