cerned in the diurnal and annual motion of the earth, or in its rotation round its axis, and in its progreffion round the fun; or, if you please, the impulse of the spirit is exerted in two different directions. The grains of the spirit, in their descent to the fun from the circumference, turn, or are fucked in by the light at the evening-edge of the line which divides light and darkness, at the cap of light; and thereby pull the western edge from the fun, and turn the eastern edge towards the fun; and fo roll the earth round from weft to eaft, and give it rotation round its axis: While the spirit at the evening-fide of the earth, pushes in a lateral direction parallel to the circle which divides the enlightened hemisphere from the dark one, and in the direction of the plane which divides light and darkness, and fo impels it forward in that plane, and gives, it progreffive motion. And as the plane which divides light and darkness, is always in the path of the ecliptic, as appears by Fig. 2. which is an orthographic projection of the earth in its annual orbit through the four cardinal points, where the direction

T

direction of the impulfe at the folftices is perpendicular to the direction of the impulfe at the equinoxes, and muft vary and make different angles in the intermediate points; fo the earth must confequently be always impelled, and fo carried round in Fig. 2. the ecliptic. Let eSg (Fig. 2.) be the

cone of light,

and eig the cone of spirit or darkness, and the cap of light; thefe two cones cover each an hemifphere of the globe of the earth, which is inclosed between them; and the line eg is the boundary of light and fpirit, or the common bafis of thefe two cones. The grains of spirit then in the line fe, in their defcent to the fun S, turn into the cap of light at é; which cap being oppofed to the action of the light from the fun, and the maffes of the spirit behind the earth being hindered from mixing with the light by the interpofition of the earth, (as above observed), is filled with light; and the reaction of its particles divides thofe maffes of spirit they find there, keep out the groffer parts on each fide, and form, comparatively to the reft of the neighbouring parts of the firmament,

mament, what is now called a vacuum: and the spirit thus turning or rushing in at e, pulls e from the fun, and turns g towards it; and thereby gives the earth rotation round its axis: and at the fame time the spirit in the lateral direction ke, pushes into the cap of light, in the faid direction, and impels the earth forward in the line eg; and the direction or application of this impulfe of the fpirit, varies as the line which is the boundary of light and spirit, varies.

eg,

AT the equinoxes, the circle which divides the light and dark hemisphere of the earth, or the folar horizon, as we may call it, cuts the equator at right angles in r and

and coincides with the poles of the globe. But it stays not in this position: for the solar light, or shemesh, as the fcriptures term it, fprings up thence, and declines to the fouth, (as Solomon fays, taking the earth to have been created at the autumnal equinox); and the circle of illumination, or the folar horizon, begins gradually to change its pofition. It no longer coincides T 2 with

with the poles, as before, but cuts the centre of the earth, and makes an angle; which is continually increafing until it amounts to 23° 30'. And this confequently varies the push or impulse of the spirit, which acts in a line which lies in the plane of the folar horizon, or circle which divides the light and darkness; and which varies as that circle varies; and as the plane of that circle lies conftantly, during the earth's annual revolution round the fun, in the ecliptic, the push or impulse of the fpirit must propel the earth in the ecliptic.

IF it be asked, When the earth is at equinox, and the folar horizon is bounded by each pole, why the spirit does not impel in the plane of that circle, and fo carry the earth forward in the æquator? I answer, So it would if the push continued in the fame direction. But the preffure of the spirit on the back of the globe, (which tends towards the fun in a line which extended would pass through the centre of the earth and the fun, and which is always perpendicular to the plane of the circle of illumi

nation,

nation, or folar horizon); this preffure, I fay, alters, every moment, the circle of illumination, or folar horizon, in the plane of which the progreffive impulse is exerted; and confequently varies the push of the fpirit. So at the folftices, the earth will, by the fame means, be brought to equinox again for the fame preffure of the fpirit at its back, or darkened hemifphere, will shift the folar horizon, or circle of illumination, in fuch a manner as that the light will gradually withdraw itself from each pole; and the lateral or progreffive impulse of the spirit, which follows the direction of the light, that is, propels in the plane of the folar horizon, or circle of illumination, will bring the earth to equinox.

To continue motion in a fluid, it is neceffary that the impulfe behind the body moved, be greater than the refiftance before; and if this can be done, it is allowed that motion may be perpetual. Now, Now, if we confider the state of the air before and behind the earth, we fhall fee that this must always be the cafe in every part of the

earth's