of less than 100 years. Jupiter falling into the sun would supply its present expenditure for 32,000 years to come; but, in view of the millions of years indicated by geological records, even this period must be considered as comparatively short. Another objection to this theory is that the quantity of matter required would, in the course of ages, add appreciably to the sun's mass, which would derange the motions of the planetary system. The meteoric theory of the sun's heat must, therefore, be abandoned.

The theory now generally accepted by astronomers is that advanced by the eminent German physicist Helmholtz, which ascribes the heat of the sun to the shrinkage of its mass caused by gravitation. It may be shown mathematically that this shrinkage would undoubtedly produce the observed result, and, as gravitation must inevitably act on the component particles of the sun's mass, it seems quite unnecessary to look further for a satisfactory theory. The amount of shrinkage required to account for the present solar radiation is so small that the diminution of the sun's apparent diameter could not be detected by the most refined instruments of measurement. Sir William Thomson has shown that this shrinkage would amount to only 35 meters on the radius per annum, or one ten-thousandth of its length in 2000 years-a quantity quite inappreciable.

According to Helmholtz's theory, the sun's heat was originally generated by the collision of two masses, as in Dr. Croll's theory, but differing from that theory in the supposition that the bodies approached each other under the effects of gravitation alone, and not with any initial velocity. In some books it is "paradoxically stated" that the sun is actually becoming hotter owing to condensation; but this is quite incorrect. As Sir William Thomson points out, "cooling and condensation go on together." In fact, as the sun has been gradually losing heat for ages past, the amount of heat lost by radiation must be in excess of that gained by shrinkage; and, as this process is probably still in progress, the sun must be actually cooling down. Of course this cooling process is excessively slow-so slow, indeed, that one estimate makes the maximum loss not more than one degree Centigrade in seven years.

According to Sir William Thomson, if the sun's heat could be maintained by shrinkage until 20 million times the present annual expenditure is radiated away, the sun's diameter would be reduced to one-half what it is at present, and its density would be increased to about the specific gravity of lead. This would probably put a stop to all further shrinkage, "through overcrowding of the molecules."

Supposing the sun to have been radiating out heat for the past 15 million years, the solar radius "must have been four times as great as at present." Sir William Thomson is not disposed to admit much more than 12 million years as the past duration of the sun's history, but, as I have shown in a former paper, this period-immense as it is-will not satisfy the demands of geologists. To meet this difficulty Dr. Croll has advanced his "Impact Theory," which has been already considered in the paper referred to (Gentleman's Magazine, June 1891).

The ancient philosophers thought that the sun might possibly be inhabited! Even in modern times this hypothesis has been seriously considered. Dr. Elliott in 1787 upheld this view, and on his trial at the Old Bailey for the murder of Miss Boydell his friends maintained his insanity and quoted as proof of their assertion the pages of his book in which this opinion was expressed. A necessary detail of Helmholtz's theory is that the sun must be in a fluid state from its surface to its centre. Were this not so it would soon grow dark, "as the conducting power of no known solid would suffice to maintain the incandescence." The idea of a solid nucleus enclosed in a fiery envelope must, therefore, be abandoned and consigned to the limbo. of all such uncritical theories.

Sir William Thomson thus describes the action which would probably take place during the formation of the sun according to the gravitation theory: "Think of two cool solid globes, each of the same mean density as the earth, and of half the sun's diameter, given at rest, or nearly at rest, at a distance asunder equal to twice the earth's distance from the sun, they will fall together and collide in exactly half a year. The collision would last about half an hour, in the course of which they will be transformed into a violently agitated incandescent fluid mass, flying outwards from the line of motion before the collision, and swelling to a bulk several times greater than the sum of the original bulks of the two globes. How far the fluid mass will fly out all round from the line of collision it is impossible to say. The motion is too complicated to be fully investigated by any known mathematical method. A mathematician with sufficient patience might, however, approximate to the truth. After a series of oscillations it will subside, probably in the course of two or three years, into a globular star of about the same dimensions, heat, and brightness as our present sun, but different from him in this, that it would have no rotation.

"If, however, each had a transverse motion-in opposite directions-of 1.82 meters per second, the result would be a globe like

our sun, rotating in twenty-five days. If the transverse velocity be anything more than o'71 of a kilometer they would escape collision, and would revolve in equal ellipses round their centre of inertia in a period of one year, just grazing one another's surfaces every time they came round to the nearest points of their orbits. If the initial transverse velocity be less than, but not much less than, o'71 of a kilometer per second, there will be a violent grazing collision, and two bright suns, solid globes bathed in flaming fluid, will come into existence in the course of a few hours, and will commence revolving round their common centre of inertia in long elliptic orbits in a period of little less than a year. Tidal interaction between them will diminish the eccentricity of their orbits, and, if continued long enough, will cause them to revolve in circular orbits round their centre of inertia, with a distance between their surfaces equal to 6:44 diameters of each."

The bearing of the latter portion of Sir William Thomson's remarks on the possible origin of binary stars will be obvious to the reader. The "violent grazing collisions" in a period of about a year seem also to suggest a possible explanation of the nature of some of the variable stars, of which the periods of several do not differ much from 365 days. Indeed, this is the theory of variable stars advanced by Professor Lockyer in his "Meteoric Hypotheses;" but in this theory the revolving masses are supposed to be swarms of meteorites, and not solid bodies. The bright lines observed in some of the long-period variables when near a maximum of light indicate a great increase of heat, which may possibly be due either to the collisions of thousands of meteorites or to solid bodies rendered incandescent by a "violent grazing collision."

J. ELLARD GORE.

NE night in the 'seventies, when the late Dante Gabriel

ON Rossetti, and the smali and intimate group whose high

privilege it was to enjoy his friendship and hospitality, were discussing poets and poetry together, someone spoke of the difficulty of expressing a sense of infinite space in a few lines, and Philip Marston quoted, as a successful example, the sestette of Rossetti's sonnet "The Choice":

Nay, come up hither. From this wave-washed mound,

Unto the furthest flood-brim look with me;

Then reach on with thy thought till it be drown'd.
Miles and miles distant though the last line be,
And though thy soul sail leagues and leagues beyond,

Still leagues beyond those leagues, there is more sea.

The next day, Rossetti was looking over "Songtide," 2 and said to Marston, "You spoke last night about the sestette of 'The Choice' being fine, Philip, but this line of yours is worth all my six," and he pointed out in the blind poet's sonnet, "Wedded Grief," the line,

Whose sea conjectures of no further land.

On another occasion, when Marston was not present, the name of Arthur O'Shaughnessy was mentioned, and the excellence of his lyrics commended.

"Yes," said Rossetti, "O'Shaughnessy has done some good work, but that Philip Marston stands at the head of all the younger men is, I think, beyond question."

This was a high testimony to Marston's ability, and when I add that Mr. Theodore Watts and Mr. Swinburne shared Rossetti's opinion in regard to the blind singer's place in poetry, it will, I think, be evident that the last poems of one who comes to us with A Last Harvest: Lyrics and Sonnets from the Book of Love. By the late Philip Bourke Marston. With Biographical Sketch by Louise Chandler Moulton. London: Elkin Mathews.

such credentials, are entitled to more than ordinary consideration. Moreover, the fact that "A Last Harvest " is published after the death of the author, gives additional interest and significance to the volume. There is always something of mystery and pathos in the birth of a child whose father is dead. To know that the parent whose features it carries will never be seen on earth again, is a strange reversal of the order of things; and, just as we scan the face of a posthumous child for some resemblance to its dead father, so do we search these poems-the posthumous children of Philip Marston's brain-for anything which may recall the singer who has gone out from us.

The first question which will be asked is, "Is the volume, or is it not, an advance upon Marston's previous achievements?" and to that question the answer is at once, "Yes" and "No." Yes, in the sense that a higher level of artistic workmanship is sustained throughout; no, inasmuch as it contains, with one exception, no sonnet or lyric which is distinctively finer in its way than anything to be found in "Songtide," "All in All," or "Wind Voices." The most notable poem in the collection is the opening one-a lyric which, in the haunting witchery of its melody, recalls Edgar Allan Poe at his best, and in which, under the metaphor of "Love's Pleasure House," Marston sings his worship of the physical beauty of womanhood

It was a

Love built for himself a Pleasure-House

A Pleasure-House fair to see

The roof was gold, and the walls thereof
Were delicate ivory.

Violet crystal the windows were,

All gleaming and fair to see-
Pillars of rose-stained marble up-bore
That house where men longed to be.

Violet, golden, and white and rose,

That Pleasure-House fair to see

Did show to all, and they gave Love thanks
For work of such mastery.

Love turned away from his Pleasure-House,
And stood by the salt deep sea-

He looked therein, and he flung therein
Of his treasure the only key.

Now never a man till time be done
That Pleasure-House fair to see
Shall fill with music and merriment,
Or praise it on bended knee.

happy thought of Mrs. Moulton's (the editor of the volume) to set this fine lyric in the entrance-hall of Philip Marston's