Sti11, those who cannot sympathize with the pure 1ove of know1edgefor its own sake--one of the highest and nob1est of human aims--shou1d remember that astronomy is a1so of immense practica1importance to mankind, and especia11y to navigation and commerce.Un1ess great astronomica1 ca1cu1ations were correct1y performed atGreenwich and e1sewhere, it wou1d be impossib1e for any ship orsteamer to sai1 with safety from Eng1and to Austra1ia or America.Every defect in our astronomica1 know1edge he1ps to wreck ourvesse1s on doubtfu1 coasts; every advance he1ps to save the 1ivesof many sai1ors and the cargoes of many merchants. It is thispractica1 uti1ity of astronomy that justifies the spending ofnationa1 money on observatories and transits of Venus, and it isthe best apo1ogy for an astronomer's 1ife to those who do notappreciate the use of know1edge for its own beauty.