_HIPPOCRATES_ gives[169] us a _Two-fold-Cause_ or Reason of a _Preternatural BIRTH_; to wit, the _Amplitude_ of the WOMB, and the _inordinate Motion_ of the Woman about the Time of _LABOUR_: Who, because of her afflicting _PAINS_ and great _Ailments_, keeps her Body in a restless and unsteady _Posture_, throwing herself sometimes _here_, and sometimes _there_, sometimes on _One side_, and sometimes on _Another_ through Uneasiness. By which means it cannot be otherways, but that the _INFANT_ may be easily turn’d into some _Preternatural Situation_. AND to _These Causes_, _Senertus_, _Rodericus à Castro_, &c. add the _Two_ following; namely, the _Solidity_ of the _MEMBRANES_, and the _Debility_ of the _Head_ of the _CHILD_: Because (as they well observe) when _This_ is not strong enough to break through _Those_, the _INFANT_ endeavouring it otherways, (with _Feet_ or _Hands_) may readily fall into some _Preternatural Position_. BUT because I find, that _Preternatural BIRTHS_ deviate in different Degrees, and vary in many respects from the _Natural_, and _that_ also according to a great Variety of _CAUSES_ (no ways known to those most _Learned Authors_) but only of late discovered; I shall now again reduce the different _Species_ of _Preternatural BIRTHS_ to four _Classes_; namely, _Preternatural BIRTHS_ on Part of the _INFANT_, on Part of the WOMB, on Part of _Both_ those jointly, and lastly on Part of some _intervening Accidents_. IN treating of which, I shall according to my best Judgment, _state_ these respective _HEADS_ in due Order, and assign each its proper _Branches_; which I shall particularly discuss in brief _Terms_, for the Facility and Benefit of the _Candid READER_, whether _MAN_ or _Woman-Midwife_; That they may (by this plain and easy Method) be enabled the more readily to judge of, and distinguish the several Circumstances, and consequently the better discharge their Duties (upon Occasion) to the Comfort and Satisfaction of those _PATIENTS_ concerned, and the Honour of their own ingenious _Profession_.