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Undoubtedly this would be true, if the earth were really to re- 

 main " always in the same part of its orbit f but the case is 

 completely altered when she moves in the same direction as she 

 rotates to a constantly increasing angular distance away from 

 the star, for then the star will be seen, or will make its transit 

 proportionally sooner every day, and, consequently, when the 

 rotation is so far incomplete. " But," our author continues, 

 " with respect to the sun, as the earth advances almost a degree 

 eastward in its orbit in the same time that it turns eastward 

 round its axis, it must take more than a complete rotation before 

 it can come into the same position with the sun that it had the 

 day before." This would be perfectly true if the sun moved 

 away from his place so much proportionally every day as to re- 

 quire an additional turning of tlie earth to overtake him ; but 

 the sun stands positively still, and the earth's meridians meet him 

 precisely in the same place every day, though not always at pre- 

 cisely the same time ; for his relation to the earth is invariably 

 the same, excepting to the small extent occasioned by his eccen- 

 tricity and the ellipticity of the earth's orbit, with which points, 

 however, we have nothing to do at present, and it will answer 

 our purpose equally well on both sides of the question, to con- 

 sider the earth's orbit as a perfect circle with the sun in the 

 centre. This relation of the sun to the earth's axis and to the 

 radius-vector that connects them, is entirely unaffected by the 

 earth's movement in her orbit, and, were the earth's orbit a per- 

 fect circle, the sun and the radius-vector would be the true mea- 

 sures of the complete rotation in respect of time as well as of 

 space. But all this I have shown fully already. Would the 

 wheel of a cart, which is always moving forward, be considered 

 to have made a complete rotation, if the spoke that was perpen- 

 dicular to the ground at one turn, should fall short of that per- 

 pendicularity at a point in advance of the former point of the 

 ground by the exact measure of the wheel's circumference ? Say 

 the wheel's circumference measures 15 feet, and it were to roll 

 along a road divided exactly into marked spaces of 15 feet each, 

 would it not at each mark present constantly the same spoke or 

 point of its circumference perpendicularly to the ground ? Why 

 then should not the earth do the same, when the marks of her 

 travelling path are as exactly measured, and as distinctly marked 

 by the sun, as any points on any road can be? The earth's 

 orbit, considered as a perfect circle, is divided into 360 perfectly 

 equal degrees, with which the sun is connected by an equal 

 number of radii at the same precisely equal distances ; his tran- 

 sits, therefore, must be the best, the surest, and, indeed, the in- 

 dispensable signs of the complete rotation of a round body moving 

 along the circle's circumference. Moreover, the extension of 



