...coincident with that plane, and perpendicular on all sides. The reef, however, continually mcreases, and being prevented from going higher, must extend...is this circumstance which renders this species of rocks so dangerous in navigation. In the first place, they are seldom seen above the water ; and in...

...surface, where they also must stop. Thus, as the level of the highest tide is the eventual limit to every part of the reef, a horizontal field comes to be formed...circumstance which renders this species of rock so dangerous in navigation. In the first place, they are seldom seen above the water ; and in the next, their sides...

...extension of the reef is at an end, not so with its lateral expansion ; and this expansion being apparently as rapid at the upper edge as it is lower down, the face of the reef everywhere preserves its steepness ; a circumstance which renders this class of rocks...

...being prevented from growing higher, extends itself laterally in all directions. But the growth being as rapid at the upper edge as it is lower down, the steepness of the face of the reef is still preserved. These are the circumstances which render coral reefs so dangerous in navigation ;...

...being prevented from growing higher, extends itself laterally in all directions. But the growth being as rapid at the upper edge as it is lower down, the steepness of the face of the reef is still preserved. These are the circumstances which render coral reefs BO dangerous in navigation ;...

...being prevented from growing higher, extends itself laterally in all directions. But the growth being as rapid at the upper edge as it is lower down, the steepness of the face of the reef is still preserved. These are the circumstances which render coral reefs so dangerous in navigation ;...

...being prevented from going higher, extends itself laterally in sill directions. But this growth being as rapid at the upper edge as it is lower down, the steepness of the face of the reef is stilf preserved. These are the circumstances which render coral reefs so dangerous in navigation ;...

...coincident with that plane, and perpendicular on all sides. SPECIMENS OF BIVALVE AND UNIVALVE SHELLS. The reef, however, continually increases, and being...circumstance which renders this species of rock so dangerous in navigation. In the first place, they are seldom seen above the water ; and in the next, their sides...

...coincident with that plane, and perpendicular on all sides. SPECIMENS OF BIVALVE AND UNIVALVE SHELLS. The reef, however, continually increases, and being...circumstance which renders this species of rock so dangerous in navigation. In the first place, they are seldom seen above the water ; and in the next, their sides...

...coincident with that plane, and perpendicular on all sides. SPECIMENS OF BIVALVE AND UNIVALVE SHELLS. The reef, however, continually increases, and being...circumstance which renders this species of rock so dangerous in navigation. In the first place, they are seldom seen above the water ; and in the next, their sides...