ates ▁for ▁their ▁increasing ▁length , ▁thus ▁pres erving ▁shapes ▁of ▁small ▁regions , ▁al beit ▁at ▁the ▁exp ense ▁of ▁global ▁dist ort ion . ▁Such ▁a ▁conform al ▁map ▁projection ▁necessarily ▁transform s ▁rh umb ▁lines , ▁sail ing ▁courses ▁of ▁a ▁constant ▁bearing , ▁into ▁straight ▁lines ▁on ▁the ▁map ▁thus ▁greatly ▁facil it ating ▁navigation . ▁That ▁this ▁was ▁Mer c ator ' s ▁intention ▁is ▁clear ▁from ▁the ▁title : ▁Nova ▁et ▁A uct a ▁Or bis ▁Terra e ▁Des cript io ▁ad ▁U sum ▁N avig ant ium ▁Em end ate ▁Ac com mod ata ▁which ▁transl ates ▁as ▁" New ▁and ▁more ▁complete ▁representation ▁of ▁the ▁terrest rial ▁glo be ▁properly ▁adapted ▁for ▁use ▁in ▁navigation ". ▁Although ▁the ▁projection ' s ▁ad option ▁was ▁slow , ▁by ▁the ▁end ▁of ▁the ▁sevent e enth ▁century ▁it ▁was ▁in ▁use ▁for ▁naval ▁charts ▁throughout ▁the ▁world ▁and ▁remains ▁so ▁to ▁the ▁present ▁day . ▁Its ▁later ▁ad option ▁as ▁the ▁all - pur pose ▁world ▁map ▁was ▁an ▁un fortun ate ▁step . ▁ ▁Mer c ator ▁spent ▁the ▁last ▁thirty ▁years ▁of ▁his ▁life ▁working ▁on ▁a ▁vast ▁project , ▁the ▁Cos m ograph ia ; ▁a ▁description ▁of ▁the ▁whole ▁universe ▁including ▁the ▁creation ▁and ▁a ▁description ▁of ▁the ▁top ography , ▁history ▁and ▁institutions ▁of ▁all ▁countries . ▁ ▁The ▁word ▁at las ▁makes ▁its ▁first ▁appearance ▁in ▁the ▁title ▁of ▁the ▁final ▁volume : ▁ ▁" Atlas ▁s ive ▁cosm ograph ica