PULSE, in the animal economy, denotes the beating or throbbing of the heart and arteries.

No doctrine has been involved in greater difficulties than that of pulses, since, in giving a physiological account of them, physicians have espoused quite opposite sentiments; whilst some doubt whether the pulse is owing to the systole or diastole, as also, whether the motion of the heart and arteries be one and the same for a given instant of time.

With regard to motion, the pulses arc reckoned only four; the great and little, the quick and slow. When quickness and greatness are joined together, it becomes violent; and when it is little and slow it is called a weak pulse. Pulses are also said to be frequent and rare, equal and unequal; but these are not the essential affections of motion. Frequency and quickness are often confounded with each other. A pulse is said to be hard or soft, with regard to the artery, according as it is tense, renitent, and hard, or flaccid, soft, and lax; for as the disposition of the arteries contributes greatly to the change of the pulse, it sometimes happens that the pulse in both arms is not alike, which is very common in hemiplexy. To these may be added a convulsive pulse, which does not proceed from the blood, but from the state of the artery, and is known by a tremulous subsultory motion, whilst the artery seems to be drawn upwards. This, in acute fevers, is the sign of death, and is said to be the pulse in dying persons, which is likewise generally unequal and intermitting. A great pulse shows [7:18:706]a more copious-afflux of the blood to the heart, and thence into the arteries; a little pulse indicates the contrary.

The pulses of persons differ according to the largeness of the heart and vessels,' the quantity and temperies of the blood, the elastic force.of The canals, and also with regard to the sex, age, season, air, motion, food, sleep, watchings, and passions of the mind. ; The pulse is larger and quicker in men than in women; in the bilious and sanguineo-bilious, than in the phlegmatic and melancholic. Those who are lean, with tense fibres and large vessels, have a greater and a stronger pulse than those who are fat, with lax fibres and small vessels; and hence they are much more healthy, robust, and apt for labour. In children the pulse is quick and soft, in adults greater and more violent. In the old it is commonly great, hard, and slow. Labour, motion, and exercise of the body, increase the circulation of the blood, the excretions, and particularly respiration; rest renders the circulation slow and weak. Animated speaking increases the circulation, and consequently renders the pulse large and quick. In watching, the pulse is more evident; in sleep, slower and more languid. After drinking hot things, such as coffee and tea, or hot-bath waters, as well as after meals, the pulse vibrates more quickly. But nothing produces a greater change in the pulse than the affections of the mind. In terror it is unequal, small, and contracted; in joy, frequent and great; in anger, quick and hard; in*sadness, slow, small, deep, and weak; and in intense study, languid and weak. With regard to the atmosphere, when, after the predominance of a west or south wind, it comes round to north or east, the pulse is stronger and larger; and also when the quicksilver rises in the barometer. But when the atmosphere is dense, humid, and rainy, with a long south wind, and also where the life is sedentary, the sleep long, and the season autumnal, the pulse is languid and small, and the perspiration decreased. In May it is great, and sometimes violent; in the middle of summer, quick but weak; in the autumn, slow, soft, and weak; in the winter, hard and great. A drastic purge and an emetic render the pulse hard, quick, and weak, with loss of strength; chalybeates and bark render it great and robust, and the complexion lively; volatiles amplify and increase the pulse; acids and nitrous remedies refrigerate the body and appease the pulse; opiates and the like render it small and weak, and decrease the elasticity of the solids; and poisons render it small, contracted, and hard. When the quantity of the blood is too great, bleeding raises the pulse.