Sound, 8 lectures1875 |
Términos y frases comunes
action aerial agitated atmosphere audible augmented beats bell burner carbonic acid caused centre column of air condensation corresponding density direction disc distance divides echoes effect elasticity embouchure experiments fog-signal fork fundamental tone gases glass hear heard heat Helmholtz Hence hydrogen inches instrument intensity interval John Herschel law of superposition layers length light liquid longitudinal membrane ment miles minor third Montlhéry motion musical sound nodal lines nodes number of vibrations observed obtained octave optical organ-pipe orifice oscillation overtones particles pass pendulum pipe pitch placed plate produced prongs puffs pulse rapidity rarefaction rate of vibration ratio reed reflected rendered resonance resultant tone rotation screen sensitive flame sonorous wave sound-wave South Foreland square stretched string surface syren temperature tion Trinity House tube tuning-fork tympanic membrane unison vein velocity of sound ventral segments vibrating segments Villejuif whistle wire
Pasajes populares
Página 398 - ... the pressure, the phenomenon became more conspicuous. The jumping of the flame gradually increased, became somewhat irregular, and finally it began to flare continuously, emitting the characteristic sound indicating the escape of a greater amount of gas than could be properly consumed. I then ascertained by experiment, that the phenomenon did not take place unless the discharge of gas was so regulated that the flame approximated to the condition of flaring.
Página 370 - ... into unisonant vibration. And thus, no matter how complicated the motion of the external air may be, these microscopic strings can analyse it, and reveal the constituents of which it is composed.
Página 71 - Glaciers of the Alps ' I have referred to a case of short auditory range noticed by myself in crossing the Wengern Alp in company with a friend. The grass at each side of the path swarmed with insects which, to me, rent the air with their shrill chirruping. My friend heard nothing of this, the insect-music lying quite bej'ond his range of audition.
Página 238 - All good and honour might therein be read; For there their dwelling was. And when she spake. Sweet words like dropping honey she did shed ; And twixt the pearls and rubies softly brake A silver sound, that heavenly music seem'd to make.
Página 370 - Within the ears of men, and without their knowledge or contrivance, this lute of 3,000 strings has existed for ages, accepting the music of the outer world, and rendering it fit for reception by the brain. Each musical tremor which falls upon this organ selects from its tensioned fibres the one appropriate to its own pitch, and throws that fibre into unisonant vibration.
Página 238 - The slightest tap on a distant anvil reduces its height to 7 inches. When a bunch of keys is shaken the flame is violently agitated, and emits a loud roar. The dropping of a sixpence into a hand already containing coin, at a distance of 20 yards, knocks the flame down.
Página 34 - ... the ratio of the specific heat of air at constant pressure to the specific heat at constant volume.
Página 44 - ... here the density being diminished, the elasticity remains the same. The velocity is directly proportional to the square root of the elasticity of the air, and inversely as the square root of the density. Sound, in fact, travels through different media with very different degrees of velocity; thus, starting with air as unity or one, the following velocities have been determined: Distilled water...
Página 407 - But from separate clouds a continuous roll of echoes could hardly come. When to this is added the experimental fact that clouds far denser than any ever formed in the atmosphere are demonstrably incapable of sensibly reflecting sound, while cloudless air, which Arago pronounced echoless, has been proved capable of powerfully reflecting it, I think we have strong reason to question the hypothesis of the illustrious French philosopher.
Página 316 - ... the most powerful fog-signal which has hitherto been tried in England. It is specially powerful when local noises, such as those of wind, rigging, breaking waves, shore surf, and the rattle of pebbles, have to be overcome. Its density, quality, pitch, and penetration, render it dominant over such noises after all other signal-sounds have succumbed. I have not, therefore, hesitated to recommend the introduction of the syren as a coast signal.