It is exceedingly difficult to assign any precise limits of pelvic contraction, within which the forceps can, and beyond which they cannot be applied, for the size and hardness of the foetal head, the nature of the pains, and the condition of the patient must also be taken into account in every instance; hence, we frequently meet with cases where the pelvis is scarcely if at all contracted, and yet where the labour has been terminated with the greatest difficulty by means of the forceps; whereas, in others where we know the pelvis to be more or less deformed, the child has been delivered by the natural powers. This subject will be still farther considered under DYSTOCIA PELVICA. The _general indications_ for the use of the forceps are two: 1. They are indicated in all labours which are difficult or impossible to complete, either from deficiency in the expelling powers, or from misproportion between the head and pelvis, or from the arm coming down with the head. 2. They are indicated by circumstances or accidental causes, which render labour dangerous for the mother or child, and where the danger can only be removed by hastening labour, as in cases of hæmorrhage, convulsions, syncope, alarming debility, faulty condition of the organs of respiration, danger of suffocation, obstinate vomiting, unusually severe pains in nervous irritable habits, hemorrhoids which have burst, hernia, retention of urine, determination of blood to the head, prolapsus of the cord, (in certain cases,) inflammation of the uterus, &c. (Naegelé, _MS. Lectures_.)