That the glottis-closing muscles are too weak to withstand a powerful expiratory pressure is therefore an entirely erroneous statement. Owing to the small area of the under surfaces of the vocal cords, the air pressure against them is very small, in comparison with the total pressure exerted on the contents of the thorax by the expiratory contraction. The glottis-closing muscles are fully capable of withstanding this comparatively slight pressure. The doctrine of breath-control is therefore scientifically untenable. This doctrine has no place in Vocal Science. As the basic doctrine of breath-control is unsound, the singer does not need any direct means for controlling the breath. The attempt to check the flow of the breath in any mechanical way is entirely uncalled for. This being the case, it is hardly to be expected that the systems devised to meet this fancied need would stand the test of scientific examination. Each of these systems of breath-control, opposed muscular action and ventricular, is in fact found on analysis to embody a misconception of scientific principles. _Opposed-Action Breath-Control_ A curious misapprehension of mechanical processes is contained in the doctrine of breath-control by opposed muscular action. This can best be pointed out by a consideration of the forces brought to bear on a single rib in the acts of inspiration and expiration. One set of muscles contract to raise this rib in inspiration, an opposed set, by their contraction, lower the rib for the act of expiration. In the opposed-action system of breath-control, the action of the rib-raising muscles is continued throughout the expiration, as a check upon the pull in the opposite direction of the rib-lowering muscles. Theoretically, the downward pull is "controlled" by the upward pull. To express this idea in figures, let the expiratory or downward pull on the rib be said to involve the expenditure of five units of strength. According to the theory of opposed-action breath-control, this downward pull would have to be opposed by a slightly less upward pull, say four units of strength. Thus graphically presented, the fallacy of the "opposed-muscular" theory is clearly exposed. The rib is lowered with a degree of strength equal to the excess of the downward over the upward pull. If the downward pull equals five units of strength, and the upward pull four units, the rib is lowered with a pull equivalent to one unit of strength. Exactly the same effect would be obtained if the downward and upward pulls were equal respectively to twenty and nineteen units, or to two and one units. Further, the result would be the same if the downward pull involved the exertion of one unit of strength, and there was no upward pull whatever. In every case, the actual result is equivalent to the excess of the downward over the upward pull.