The motions of the child itself can now be generally both felt and seen, and an experienced observer may even predicate from them, with tolerable certainty, the position in which it lies. Ballotment, by one hand on the Abdomen, may still be practised with success; but in the Vagina it is difficult, because the Fœtus is both more fixed and heavier. Auscultation is now the surest dependence however, and may be advantageously resorted to also as a means of determining beforehand the position of the child. This may be done even a month earlier, but not so certainly as now. To understand how this important point is determined, it is only necessary to recollect, as will be very evident, that the pulsation will be heard the loudest immediately over the heart; and as we know the form and general size of the Fœtus, and the manner in which it usually lies, it becomes possible, when the position of its heart is discovered, to trace out, from that, the position of every other part. This will be evident by referring to Plates XIX, XX, and XXI. It will then be seen that, if a line be drawn across the middle of the Abdomen, the heart will be _above_ that line when the breech presents, and _below_ it when the head presents, and on the right or left side, as the case may be, in each position. In case of twins there will be two pulsations, and they so much interfere with each other that it is difficult to distinguish either. The two children being generally disposed with the head of one to the heels of the other, one heart will be _above_ the line, and the other _below_, on opposite sides, as shown in Plate XXII. PLATE XIX. This Plate represents the Fœtus in the most usual position, the head downwards, and the back of it presenting to the _left_ side. The black spot _a_, shows the situation of the heart; usually immediately under that part where the sound is heard the strongest.--It is below the line. [Illustration: Plate XIX. This Plate represents the Fœtus in the most usual position, the head downwards, and the back of it presenting to the _left_ side.] PLATE XX. This Plate represents the Fœtus in the next most frequent position, the head downwards, but the back of it presenting to the _right_ side. The black spot _a_, shows the situation of the heart as in the previous Plate. It is now below the line, as before, but on the opposite side. [Illustration: Plate XX. This Plate represents the Fœtus in the next most frequent position, the head downwards, but the back of it presenting to the _right_ side.] PLATE XXI. This Plate shows the position of the Fœtus in a presentation of the Pelvis, or breech, which happens, comparatively, but seldom. The black spot _a_, denotes the situation of the heart, which is here _above_ the line, instead of below. In this case, as in the others, the heart may be on either side of the body, according as the child faces, but always above the line. [Illustration: Plate XXI.