There is, however, another kind, which differs a little from this I have been describing, but is nevertheless to be considered as a modification of Night-Mare, arising from the same cause, and requiring the same remedies; for which reason I shall include it in my History of that disease. I mean that undescribable terror which some persons feel in their sleep, and which frequently obliges them to vociferate loudly, and generally to start with violence, or sometimes even to jump out of bed. This terror is often, perhaps mostly, accompanied by some really terrific dream. This is not always the case, however, and when it does happen, the dream is rather to be considered as the effect of the terror, than the cause of it. I have frequently found this terror to be connected with some object, not at all in itself terrific; as for instance, a cat or a dog, or sometimes a little child which I had been contemplating in my dream for some time without any dread or terror, has all at once become an object of the utmost horror and alarm, and that without at all changing its appearance or attitude. A sudden panic has struck me with a degree of terror, which I am convinced nothing on earth could produce in me when awake; and which obliges me to vociferate with uncommon vehemence, and to start with so much violence as generally to wake myself immediately, and frequently great part of the family beside. It would be impossible by any words, to convey an adequate idea of the terror felt during this affection: the patient continues to feel it for several minutes after he is awake; at least it requires some little time for even a strong mind to recover its tranquillity. I have always observed in my own case, as well as in all those I have had the opportunity of investigating, that this kind of affection is universally accompanied with a sensation called shivering; not precisely of that kind which accompanies the paroxysm of ague, but that momentary sensation of shivering which people are apt to feel on hearing any tale of horror related, or frequently indeed, without any evident cause whatever. It is a vulgar opinion, that this shivering takes place whenever any one is walking over the future grave of the person who feels it. This kind of shivering is, at all times, accompanied with some degree of horror, and that has probably been the reason of the superstitious opinion above mentioned. Hence also the common expression, on hearing a tale of horror, that _it makes the blood run cold_; which is precisely the sensation of the person, both in the dreams themselves which we are speaking of, and for some little time after waking out of them. This sensation is always referred to the spine, and appears to descend from the neck to the loins. The cause of it is not very easy to explain; it evidently belongs to that class of sensations and affections which we call nervous, and appears in this case to be the immediate cause of that terror which invades us in