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130 come to light, and some supposed concords have had to be given up; so that were he alive to-day he would himself have formulated some other scheme. Two, however, are still as true: that the planets all revolve in the same plane and in the same sense, and that sense that of the Sun's rotation. But so general a congruity as this points only to an original common moment of momentum and is equally explicable however that motion was brought about. It seems quite compatible with an original shock. To say that it was caused by a disruption is simply to go one step farther back than Laplace. If, then, such a catastrophe did occur as the meteorites aver, we may perhaps draw some interesting inferences about it from the present state of the system. In a very close approach such as we must suppose for the disruption, one within Roches' limit of 2.5 diameters, the stranger, supposing him of equal size, would sweep from one side of the former Sun to the other in about two hours, and the brunt of the disrupting pull occur within that time. That the former Sun was rotating slowly seems established by the time, twenty-eight days, it now takes to go round. In which case the orbits of the masses which were to form the planets would all lie in about the same plane,—the plane of the tramp's approach. If there were exceptions, they should be found in the innermost. For such should partake most largely of the Sun's own original