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the back in curls; the same holes are seen on the neck as of ringlets, and the sword-belt may also be traced over the shoulders.

The two small female statues on the apex were found entire, except the heads and the left hands holding the pomegranate flowers; their feet, on a small plinth, were still attached to the ornamental pedestal on which they stand; we recognize in them the well known costume and attitude of the Ελπίς of the Greeks, of which the various museums and coins furnish so many examples exactly similar in every respect, and in the most archaic style. Although various passages of ancient authors and the number of statues of this goddess, sufficiently attest her importance amongst the Greeks; yet we have no mention of temples to her honour in any instance of a similar application*. It cannot but appear, however, that while they are highly ornamental they are also singularly appropriate to the subjects beneath them, for while the battle is suspended Hope might still preside†.

In Plate II. the small female head belonged to corresponding figures in the East of a dimension somewhat larger; various fragments of them as traced were found, sufficient to prove their general similarity, though not enough to restore them even on paper. The hair, curled with great care, is confined by the σφενδονη, the ear-rings are cut in the marble. It will be observed also, that the apex, by the various fragments of it discovered, was on a much larger scale, corresponding with the proportionally greater importance, and the number of the statues and richness of composition and decorations in the East front.

We have various examples of ancient bas-reliefs, as well as passages † which represent Fortune as the companion of Hope. In the temple of Jupiter at Olympia, a victory on the apex was placed; it is possible these might have had the same signification, and it would seem that where Minerva takes a decided part,

* See Museo Vat. vol. iv. Tav. viii. and vol. vii. Tav. xx. Visconti's description of the Candelabra, &c. in Museo Etrusco, Tav. xxvi.

↑ Theogn. v. p. 37, Vas. di Salviani, p. 71. and Antholog. lib. 1, cap. xxv. Nos. 2 and 3. Vol. VII.

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Victory would attend her; with the same propriety, Hope should be present while the contest is undetermined.

The acroteria on the apex in the West, as before observed, was found nearly entire, Its nice construction and manner of adapting it to the roof and tiles, and the exquisite perfection of every part of it excited our wonder and admiration; it is of Parian marble also. The griffins or chimera surmounting the angle of the pediment (see Plate II.) were found at each corner of the temple, and though much broken, fragments enough were found to give complete authority for their restoration in drawing, except the head, which is taken from the Teian medals; it was a portion of one of these which Chandler discovered in his hasty excavation at this temple, and mentions as the legs of a greyhound.

The lion's head attached to the extreme tile was found perfect, and in the blocking which carries the chimera was a sinking, corresponding with the thickness of the plinth to which the legs were attached.

It is hardly necessary to repeat, that the whole of the ornaments indicated on the several members of the cornice were painted on the marble in encaustic; as are the extreme tiles, forming the upper moulding of the pediment, and on the stone of which the whole temple was constructed, is a thin coat or varnish of very fine and hard plaster.

ART. IV. On the Periodical Suspension and Renewal of Function, observable in the Human Body. By J. R. Park, M. D.F.L.S. & M. R.I.

ON THE CAUSE OF SLEEP.

THE most remarkable instance of periodical intermission of function is that attendant upon sleep; and it may excite surprise in the minds of those who are not aware of the imperfect state of our knowledge of the animal economy, to find this familiar affection classed amongst those phenomena which the physiologist is unable to explain or account for.

That the nature and cause of sleep have never been truly as

certained, appears from the discordance of opinion that still prevails amongst the most eminent writers respecting the physical state of the brain which produces it.

How much our ignorance on this subject is to be lamented, may be readily appreciated by reflecting, that a disturbance, or morbid change of this affection, forms a prominent feature in many formidable diseases; and the physician cannot be supposed to possess an adequate knowledge of their nature, whilst he remains unable to account for one of their leading symptoms.

But the importance of the subject may be placed in a more striking point of view.

The operations termed mental immediately proceed from the brain, which is as much the organ of mind, as the eye is the organ of sight; and the state of the mental powers as much depends upon the condition of the organ of mind, as the sense of vision depends upon that of the organ of sight.

Now sleep, which is a temporary suspension of the mental faculties, is almost universally ascribed by physiologists to a peculiar state of the brain; but if the nature of that state, or of those changes which produce a periodical remission and renewal of activity in the brain be unexplained, it is evident that the laws are not yet ascertained, by which its function is governed. And it is not to be conceived, that the real nature and cause of morbid derangements, or aberrations of the mind can be known, whilst the knowledge of its healthy function is wanting.

The physical cause of sleep is a question then, which involves some of the most interesting problems in medical science; and its solution is, in fact, indispensable as a preliminary step to the consideration of others more immediately practical which will follow.

To expose the errors and inconsistencies of others is an ungracious, and far from a pleasing task; but where it is essential to the establishment of truth, as in the present instance, it cannot be dispensed with.

Sleep is described by most physiological writers, as a suspension of function exclusively confined to the organs of voluntary motion and mind. But the same authors, when inquiring into the physical change which occasions it, nearly all concur in ascribing it to a peculiar state of circulation in the brain.

Now circulation belongs neither to the class of mental nor voluntary functions, but is decidedly involuntary or automatic. If sleep then proceed from change of circulation, it originates in the vascular system; and the vessels being involuntary organs, it is surely inconsistent and erroneous to regard the remission of action which occasions it, as peculiar to mental and voluntary functions.

That sleep really does arise from change of circulation in the brain, as these authors admit, it is the object of the present essay to demonstrate; but at the same time to point out more precisely than has hitherto been done, the nature of that change; and moreover, to ascertain its cause, which these writers have not investigated.

The cause of this change of circulation will be found similar to that which produces periodical fluctuations of activity in other moving organs; or the subjection of the vascular system to the general laws of fibrous contraction. And the influence, which this change exerts over the mental faculties, will be seen to accord in every respect with the influence of altered circulation on other functions.

But before we proceed to the illustration of this doctrine, it will be proper to state more particularly the opinions of former writers respecting the physical cause of sleep.

This statement, as it regards some of them, must unavoidably bring into view a circumstance little calculated to inspire confidence in the accuracy of their reasonings; which is, that sleep is ascribed by different authors to diametrically opposite states of circulation; namely, by some, to too much, and by others to too little blood in the cerebral vessels.

It is singular, that these authors in ascribing sleep to altered circulation, should not have been prompted to investigate the cause of the periodical change of vascular action thus implied and admitted. Such an inquiry might have led to the detection of that important principle in pathological science, the subjection of the vascular system to the general laws of muscular action. And it might further have been expected, that, the connexion which in this instance was perceived, and tacitly allowed to prevail between the activity of the mental powers, and the state of circulation in the brain, would have directed the attention of physiologists to a more strict examination of the same connexion in other organs and other functions.

This examination would have led to the detection of the other equally important principle, that, the state of every function immediately depends upon the actual condition of its capillary

vessels.

Upon these two points, the foundation of pathological science may be said in a great measure to rest; and sleep, as well as every other suspension or remission of function, results from the operation of these laws.

To return to the opinions of former writers, the following are the views offered by the most eminent authors.

Sleep is ascribed by Cullen to collapse of the brain, by which is to be understood, as he explains (in his Institutions of Medicine, Part I. p. 95), a state of diminished mobility in the nervous fluid.

Darwin and Brown referred sleep to the diminution of excitability or sensorial power in the brain, which according to their views is expended during the day, and re-accumulated during sleep.

Haller, after shewing the probability of cerebral congestion, comes to the following conclusion: "Sleep, therefore, arises either from a simple absence, deficiency and immobility of the spirits; or from compression of the nerves; and always from the motion of the spirits through the brain being impeded. (See First Lines of Physiol. Transl. p. 285.)

Richerand disputes the doctrine of pressure from blood accumulated in the brain causing sleep; and, on the contrary, after enumerating the circumstances that denote a diminished circulation, he concludes, " that the brain falls into a state of collapse during its continuance; a proof that the quantity of blood carried to it is considerably diminished." (Elements of Physiol. p. 294. translation, London, 1807, 2d edit.)