The orbits are always open behind, never being surrounded by bone.
The first, for a memoir on the construction of a clepsydra for measuring time exactly at sea, he gained at the age of twenty-four; the second, for one on the physical cause of the inclination of the planetary orbits, he divided with his father; and the third, for a communication on the tides, he shared with Euler, Colin Maclaurin and another competitor.
The squamosals form the posterior outer margin of the orbits and are frequently continued into two lateral downward processes across the temporal fossa.
It is also remarkable that all the great planets and many of the small ones have their orbits very nearly in the same plane, and nearly circular in form.
In this way we account most simply for the uniformity in the direction in which the planets revolve, and for the mutual proximity of the planes in which their orbits are contained.