1886.] NEW YORK ACADEMY OF SCIENCES. 235 



on observations at Pulkowaand Greenwich, and leading to a sus- 

 picion tliat the axis of the earth is slightly changing its position 

 and sliifting the place of the poles on the earth's surface. Opera- 

 tions have been organized to determine the question, by co-opera- 

 tion between different observatories in nearly the same latitude, 

 but widely differing in longitude. 



Nor ought we to pass unnoticed an elaborate paper by Kap- 

 teyn, of Groningen, on the determination of latitude by a method 

 depending upon time-observation of stars, at equal altitudes, 

 though in widely different parts of the sky ; the stars being so 

 selected that all errors of star-places, instrument, and clock, are 

 almost perfectly eliminated. In the same connection we ought 

 to mention also the new equal-altitude instrument, the Almu- 

 cantar, invented by Chandler, of Cambridge, and his develop- 

 ment of the method of determining time by its use. It may 

 possibly supersede the transit instrument for this purpose, as he 

 seems to expect, though we think it hardly likely. 



Eapid progress has been made in determining the difference of 

 longitude between all the principal parts of the earth. There 

 now remain very few stations of much importance, which have 

 not their longitude from Greenwich telegraphically settled within 

 a small fraction of a second. In Europe, Albrechthas combined 

 into a consistent whole all the different data for more than one 

 hundred points. Our American system has been similarly worked 

 out by Schott, and is connected with the European by no less than 

 four different and independent cable-determinations. South 

 America is connected with the United States by the recent opera- 

 tions of our naval oflBcers in the West Indies and along the 

 eastern and western coasts of the continent : and with Europe 

 by a cable connection between Lisbon and Pernambuco, also ef- 

 fected by them. It is worth noting that two large errors in 

 Earope;in longitudes owe their detection to American astrono- 

 mers. The difference of longitude between Greenwich and Paris 

 was corrected by our Coast Survey in 1873 to the extent of nearly 

 half a second of time, and our naval officers in 1878 showed that 

 the then received longitude of Lisbon was 8.^54 too small ! It is 

 a less surprising fact that an error of 35 ^ was found in the lon- 

 gitude of Kio. 



Our navy has also determined an important series of tele- 

 graphic longitudes along the eastern coast of Asia and through 

 the East Indies. The French have been doing similar work 

 in the same regions, especially in connection with the transits of 

 Venus ; and the English have determined a large number of 

 longitudes in India. These Asiatic longitudes have been recently 

 connected with Australia and New Zealand by English astrono- 

 mers, and a telegraphic longitude connection has been effected 



