Gyroscope

Collier's New Encyclopedia (1921)

an instrument constructed by M. Foucault, to make the rotation of the earth visible. The principle on which it proceeds is this-that, unless gravity intervenue, a rotating body will not alter the direction in which its permanent axis points. In the gyroscope there is a rotating metallic disk, the middle point of whose axis is also the center of gravity of the machire. By this A B GYROSCOPE A. Gyroscope. B. Gyroscope as used in torpedo. device the action of gravity is eliminated. The instrument, moreover, is so constructed that the axis of rotation can be made to point to some star in the sky. Then, as the heavy disk whirls round, it is found that the axis continues to point to the moving star, though, in consequence of this, apparently altering its direction relatively to bodies on the earth. If, again, the axis be pointed to the celestial pole, which is fixed, no alteration in its position relative to bodies on the earth takes place. The only feasible explanation of these appearances is that the earth is revolving on its axis. The gyroscope has been a valuable adjunct as a stabilizer in the making of aeroplanes. H, h, the eighth letter of the English alphabet, commonly classed among the consonants, though not strictly such. It is frequently called the aspirate, though other letters are also aspirated in English. Its distinctive or proper sound is that which it has at the beginning of a word, as help, hard, hope, etc. This sound it also has when following w, as in whither, where, in which cases it originally preceded the w, as in Old English, hwidir, hwær. H has disappeared especially before bef 1, n, from many words, es Old English, hlaf=loaf; Old Engr: as, Old En ring; Old English feoh=fee. It has been intruded into into some words as wharf, whelk, whelm. H is commonly joined to other consonants to form digraphs representing sounds for which there are no symbols in the alphabet; as, ch in child, chill; sh in shin, ship; th in this, that, thine; joined with pit forms the sound of f; with g it sometimes forms the sound of f, as in enough, tough; sometimes the digraph is silent, as in bough, plough. The combination rh is found only in words derived from the Greek, where the h represents the rough breathing of the original rh. Ch is common in words derived from the Greek, and in such cases is generally hard, as chemistry, chyle, etc. It sometimes represents the Latin c, Greek k, as in English horn Lat. cornu, Gr. keras.