’Tis highly probable that the Motion of the Blood is renew’d before any of the Voluntary Motions are recovered; for we never find that any of the Voluntary Motions remain after the Motion of the Heart ceases; and the surprising process of generation shews, that the first Motion observable in animal Bodies, is that of the Heart[14]. We have many instances, in Brutes, of the Heart’s Motion continuing long after the action of the Voluntary Muscles is quite destroy’d[15]. It is not improbable, that the human Heart would contract itself after Death, if the same experiments could, with any degree of humanity, be tried on it, that are made on the Hearts of Brutes: and the great Lord Bacon gives an instance of a criminal’s Heart, which he saw, after torn from the Body, leap up and down for several minutes[16]. In a severe fit of the Night-mare, when the Motion of the Blood, and consequently the Motion of the Heart, is stop’d, the Mind, must be in a terrible agony; and the only chance it has for further communication with the Body, depends upon the vigour and sensibility of the right or superior Ventricle of the Heart; for, if it be not able to push the Blood through the Lungs, and overcome its own weight at the same rime, de Vita Actum est. From what has been said it appears, that lying on the Back is a dangerous, uneasy position, and should be carefully avoided, even when we are awake. I believe few can lie long on the Back without feeling an uneasiness in the Breast, which is soon remov’d by turning on either Side: but when People are buried in sleep, and are incapable of that action, the consequence is dreadful, for the reason often mention’d. We may be convinc’d, that, if lying on the Back would not impede the Vital Motions, nature would have directed us to chuse that position in sleep, because it requires scarcely any muscular action. But, on the contrary, we find that most of the human species prefer lying on either Side. As colonel Townshend’s case is a remarkable instance of the dangerous effects which may proceed from lying on the Back, and as it may serve to illustrate my theory of this Disorder, I shall here quote it at full length, that the reader may the more readily observe the analogy between his mechanical suppression of the Vital Motions, and a fit of the Night-mare, It is thus related by Doctor Cheyne, in his English Malady[17]. The CASE of the honourable Colonel TOWNSHEND.