The remarks made by Dr. A. Clarke on this point, will, it is presumed, gratify the intelligent reader. “The _double motion_ of a primary planet, namely, its _annual_ revolution and _diurnal_ rotation, is one of the greatest wonders the science of astronomy presents to our view.--The laws which regulate the latter of these motions are so completely hid from man, notwithstanding his present great extension of philosophic research, that the times which the planets employ in their rotations can only be determined by observation. How is it that two motions, so essentially different from each other, should be in the same body, at the same time, without one interfering at all with the other?--No astronomer, since the foundation of the world, has been able to demonstrate that the earth’s motion in the heavens is at all accelerated or retarded by the diurnal rotation; or, on the other hand, that the earth’s motion on its axis experiences the least irregularity from the annual revolution.” The rotation of the earth round its own axis, from west to east, once in 23 hours, 56 minutes, 4 seconds, is the cause of the distinction between day and night, by bringing the different parts of the earth’s surface successively into, and from under the solar rays. And the revolution of the earth round the sun, from any equinox or solstice to the same point again, in 365 days, 48 minutes, 48 seconds, produces the agreeable vicissitudes of the seasons, and measures the length of our year. For though the revolution is that of the earth, yet both the hours of the day and night, the different lengths of the days and nights, and the seasons of the year, cannot be determined but by the heavenly bodies. Thus the earth has a two-fold motion, like a chariot-wheel; for while it goes forward on its annual journey, it is still in its diurnal motion turning upon its own centre. But it differs from the motion of a chariot-wheel in this: that its hourly motion in its orbit is 75,222 miles; and that by the motion upon its axis, the inhabitants on the equator are carried after the rate of 1,042 miles an hour, and those upon the parallel of London 580 miles. The Dr. proceeds, “How wonderful is this contrivance! and what incalculable benefits result from it! The uninterrupted and equable diurnal rotation of the earth gives us day and night in their succession, and the annual revolution causes all the varied scenery of the year. If one motion interfered with the other, the return of the day and night would be irregular; and the change of seasons attended with uncertainty to the husbandman. These two motions are, therefore, harmoniously impressed upon the earth, that the gracious promise of the great Creator might be fulfilled, ‘While the earth remaineth, seed-time and harvest, and cold and heat, and summer and winter, and day and night, shall not cease.’