Philosophical Transactions, Volume 3…
“ Why Comets are almost never perceiv'd' by Us, when they first emerge out of their Atmosphere? That, the motion of Comets hath a conformity with that of Ships. That the Sun does the same in the deviation of Comets, what a Pilot or Ship-master doth by the meanes of Cables in the direction of Sayling. That Comets, like Ships, describe sometimes an entire, sometimes a Semi-parabola. ”
