The position of the head in its influence on tone-production is an insufficiently considered subject. It is impossible that the head be much raised or lowered without changes being produced in the vocal apparatus, especially the larynx, and if the tone is not to suffer in consequence, special care must be taken to make compensatory changes in the parts affected. It is only necessary to sing any vowel, and then raise the chin greatly, to observe a distinct change in the quality of the tone, with corresponding sensations in the vocal organs. To speak or sing with the head turned to one side is plainly unfavorable to the well-being of the parts used, because it leads to compression, which gives rise to that congestion before referred to as the source of so many evils in voice-users. To sit at a piano and sing is an unphysiological proceeding, because it implies that the head is bent in reading the music on a page much lower than the eyes, and when, with this, the head is turned to one side to allow of reading the music on the distant side of the page, furthest from the middle line of the head, the case is still worse. If all who thus use the vocal organs do not give evidence of the truth of the above by hoarseness, etc., it is simply because in young and vigorous organs there may be considerable power of resisting unfavorable influences. The student is recommended to use his voice in the standing position only, when possible, as all others are more or less unnatural. One often has the opportunity to observe how the effect is lost when a reader bends his head downward to look at his book or manuscript; and he himself, if the process is long-continued, will almost certainly feel the injurious influence of this acting on his vocal organs. CHAPTER XIV. SOME SPECIFIC APPLICATIONS OF PRINCIPLES IN TONE PRODUCTION. It is no doubt valuable, indeed for most singers essential, to employ a series of elaborate exercises, or _vocalises_, which in some cases differ from each other only by slight gradations; but it is to be borne in mind that all the actual principles involved can be expressed practically in a very few exercises. These are: (1) The single sustained tone; (2) the tones of a scale sung so as to be smoothly linked together; (3) the same, sung somewhat more independently of each other; (4) the same, but each tone beginning and ending very suddenly. If the execution of any vocal musical composition be analyzed, it will be found that these four methods cover substantially the whole ground. As one other is very extensively used in giving expression in the form of shading, it is worthy of special mention--viz., (5) the swell. All others are modifications of the above.