Of rhythm, then, there are two varieties, the rhythmic and the arhythmic. Of the arhythmic, there is a threefold difference: first, when there is a slight departure from rhythm; second, when there is a greater; and third, when there is no rhythm at all. Thus, for example; in a child, if his pulse has the rhythm of childhood, it is called its proper rhythm; if it has that of an adult, it is said to be an improper rhythm; or if it preserve no ratio at all, it is said to be devoid of rhythm. The ninth kind of pulses is found in all the other kinds already mentioned; namely, that which regards equality and inequality, which may be remarked either in one pulse, or in many, which last is called the systematic, of which we must speak first, as being more clear. An _equal_ pulse, then, is that which is alike in order, as regards magnitude, strength, frequency, and certain other, or indeed all its other, characters. The _unequal_ pulse is that which is unlike in order. For, if all are alike, as, for example, all deficient in magnitude, such a pulse is called equal. But if the first, second, and third appear alike, but the fourth unlike, it is clear that such a pulse is _unequal_ as to magnitude. Of this kind are the _intermitting_ and the _intercurrent_. For not only after one or more great pulsations may one smaller occur; but sometimes this motion is wholly lost, and one pulsation is said to be wanting. The other kind, the intercurrent, is the opposite to this; for when we are expecting an interval of rest, a supernumerary pulsation, as it were, occurs. When the second is a little smaller than the first, and the third than the second, and the fourth than the third in like manner, and so onwards, such pulses are called _sharp-tailed_ or _myuri_, deriving their names from figures terminating in a sharp point. Such as are altogether diminished, and never cease from this state, terminate in a total loss of motion, and are called _failing_ or _fainting myuri_. There are two varieties in respect to those which fail, for some of them persevere in that state of smallness in which they terminated, whilst others attain again their original magnitude, or less or more, and these are called _recurrent myuri_. Pulses also are called myuri, from their inequality in regard to one pulsation, concerning which we will speak presently. And this is the nature of that inequality of pulse, called systematic. But it takes place with regard to one pulse, or one part of an artery, or more, as perhaps with regard to motion, for the inequality is observed on one part of the artery, when the motion of the artery upon the finger begins one way and terminates another, beginning quicker, and terminating slower, or reversely. This happens in a threefold manner, the motion either remaining constant, or being interrupted, or recurring and beating double, as it were. If, then, remaining constant and uninterrupted, it should change from quickness to slowness, or