In conducting the auscultation the female must recline, and keep as still as possible, breathing low. The Abdomen may be covered with a single thin garment, if absolutely insisted upon; but the judgment will be so much the more uncertain, owing both to the deadening of the sound and to the friction of the material. The experimenter must also recollect that if the head be held down too long, the blood will rush to it, and cause a humming in the ears, which will confuse him; it will therefore be better if the bed be high. It is always best to use the _stethoscope_, as it covers only a small space, conveys the sound more directly, and shuts out external noises more effectually. This instrument is extremely simple, consisting merely of a tube of wood, glass, metal, gum elastic, or almost any other material. One end should be expanded a little, like a bell, and the other made small, so as to fit close in the ear--the large end being placed on the Abdomen. It may be about a foot in length, though a little shorter or longer will not make much difference. I once used a child's _tin trumpet_, having no regular stethoscope with me, and succeeded with it perfectly. The large end should be pressed on the Abdomen, and the smaller one into the ear, sufficiently close to shut out all other sounds but those coming from the body. This is the same instrument that the lungs are sounded with, when we want to judge of their action and condition. This is an invaluable means of detecting pregnancy; in fact, at the proper time, and with due care, it may be said to be _certain_. _End of the sixth month._--This is the period when, according to the law, the child can live. There are no new signs at this time, but those previously noticed are now more distinct. The neck of the womb is still softer and shorter, and the finger can penetrate further in the passage than before. The fundus of the womb is now above the umbilicus, in primipara, though not so high in those who have borne children; and the bladder is above the superior strait. Ballotment can now be practised with certainty, the falling and rising of the Fœtus being very distinct. Auscultation also becomes more positive, the sounds being louder and more easily ascertained. _End of the seventh month._--The fundus of the womb has now risen still higher, and the Bladder is pushed completely above the upper strait, so that the whole length of the Urethra lies behind the pubic bone. It is then much pressed upon and swollen, and being much longer, and bent out of its usual course, the urine is often passed with difficulty, and the catheter can scarcely be introduced. The upper part of the Womb now lies over towards the _right side_ of the body, very evidently. This direction is nearly constant, in all females, but the reason for it is not known. There have been many theories to account for the peculiarity, but none of them are either so plausible, or so well supported by facts, as to be generally adopted.