No astronomical instruments had been brought along during the frontier expedition in this region, so with my chronometer, and by the meridional height of the stars, I established the exact location of San Baltasar de Atabapo, Javita, San Carlos de Río Negro, the Culimacarai rock and the Esmeralda mission. The map I drew has resolved any doubts about the reciprocal distances between the Christian outposts. When there is no other road but the tortuous and intricate river; when little villages lie hidden in thick jungle; when in a completely flat country with no mountains visible, you can read where you are on earth only by looking up to the sky.