e closing together.

Sir William Herschel was the first to discover this motion of the sun
through space; though in the idea that such a movement might take place
he seems to have been anticipated by Mayer in 1760, by Michell in 1767,
and by Lalande in 1776.

A suggestion has been made that our solar system, in its motion through
the celestial spaces, may occasionally pass through regions where
abnormal magnetic conditions prevail, in consequence of which
disturbances may manifest themselves throughout the system at the same
instant. Thus the sun may be getting the credit of _producing_ what it
merely reacts to in common with the rest of its family. But this
suggestion, plausible though it may seem, will not explain why the
magnetic disturbances experienced upon our earth show a certain
dependence upon such purely local facts, as the period of the sun's
rotation, for instance.

One would very much like to know whether the movement of the sun is
along a straight line, or in an enormous orbit around some centre. The
idea has been put forward that it may be moving around the centre of
gravity of the whole visible stellar universe. Maedler, indeed,
propounded the notion that Alcyone--the chief star in the group known as
the Pleiades--occupied this centre, and that everything revolved around
it. He went even further to proclaim that here was the Place of the
Almighty, the Mansion of the Eternal! But Maedler's ideas upon this point
have long been shelved.

To return to the general question of the proper motion of stars.

In several instances these motions appear to take place in groups, as if
certain stars were in some way associated together. For example, a large
number of the stars composing the Pleiades appear to be moving through
space in the same direction. Also, of the seven stars composing the
Plough, all but two--the star at the end of its "handle," and that one
of the "pointers," as they are called, which is the nearer to the pole
star--have a common proper motion, _i.e._ are moving in the same
direction and nearly at the same rate.

Further still, the well-known Dutch astronomer, Professor Kapteyn, of
Groningen, has lately reached the astonishing conclusion that a great
part of the visible universe is occupied by two vast streams of stars
travelling in opposite directions. In both these great streams, the
individual bodies are found, besides, to be alike in design, alike in
chemical constitution, and alike in