A. MATHEMATICS AND ASTRONOMY. 19 



longitudes in the southern hemisphere. In Southern Africa 

 and in Australia the telegraph lines already offer facilities 

 for most extensive geograjihical operations ; but we believe 

 the principle work that has as yet been done in the southern 

 hemisphere has been recently effected by Dr. Gould, the di- 

 rector of the National Observatory at Cordoba. During the 

 past year he has made such determinations between his own 

 central observatory and the cities of Buenos Ayres and Ro- 

 sario to the eastward. As the result of this work, he announ- 

 ces an error of one minute of time in the relative longitude 

 of these places as given on the best maps. Preparations 

 have also been made for longitude work between Cordoba 

 and Santiago de Chili, but the accounts of the results of this 

 w^ork have not yet been received. 



NEW LIVERPOOL OBSEEVATOEY. 



One of the most important services that astronomy has 

 rendered to mankind consists in the contributions it has 

 made to the progress of navigation, and th6 increased se- 

 curity of life and property. In this field England has always 

 taken the lead, and the efforts of Mr. Ilartnup at Liverpool 

 are a w^orthy continuation of the labors of Flamstead, Brad- 

 ley, and Airy. While the Greenwich Observatory has caused 

 a great improvement in the general standard of the chro- 

 nometers bought for the use of the government vessels, Mr. 

 Hartnup has sought to effect a similar reform for the mer- 

 cantile marine. He has insisted on the vital importance to 

 ship-masters, as well as to owners and insurance companies, 

 of the careful determination of the rates of their chronome- 

 ters as affected by temperature. The makers of these in- 

 struments, and the astronomers who use them carefully, have 

 always known that which captains of vessels have been very 

 slow to profit by ^. e., that the chronometers are, when 

 made, so adjusted that they keep perfect time at two tem- 

 peratures, such as 55 and' 85 Fahr., while between these 

 limits they gain, and beyond them they lose, on the true time. 

 It is rare that this variation in the chronometer rate can be 

 safely overlooked by a careful navigator, though it is fre- 

 quently done by those whose vessels do not cany a pre- 

 cious burden of one or two thousand souls. The only excuse 

 for this neglect is the positive assurance of the maker that 



