Pulsation

“ Whether the pulsation will start up or not depends on whether the engine of pulsation is sufficiently powerful to overcome the forces tending to damp out and dissipate pulsations. We cannot predict the occurrence or non-occurrence from any settled theory; we have rather to seek to frame the laws of release of subatomic energy so as to conform to our knowledge that the majority of the stars remain steady, but certain conditions of mass and density give the pulsatory forces the upper hand. ”

“ Irregularity of the pulse generally indicates disease, and there are two varieties of it. In most instances of irregular pulse, succeeding beats differ in length, force and character; in the other variety a pulsation is from time to time left out; the pulse is said to intermit. ”

“ For we must not confound frequency of repetition with quickness of motion, or the number of pulsations with the velocity, with which the fibres, which constitute the coats of the arteries, contract themselves. For where the frequency of the pulsations is but seventy-five in a minute, as in health; the contracting fibres, which constitute the sides of the arteries, may move through a greater space in a given time, than where the frequency of pulsation is one hundred and fifty in a minute, as in some fevers with great debility. ”

“ But, truly, as has been stated, both in the chick in ovo and in the moribund animal, if you but apply some gentle stimulus either to the punctum saliens or to the right auricle of the heart after the failure of all pulsation, forthwith you will see motion, pulsation, and life restored to the blood—provided always, be it{377} understood, that the innate heat and vital spirit have not been wholly lost. ”

“ The neighbourhood of certain joints where the pulse can be felt most readily, and the top of the head, where pulsation can be felt in the infant's fontanelle, were therefore regarded by some Asiatic peoples as the places where the substance of life could leave or enter the body. ”

“ Sixteen pulsations in a second are necessary to produce the lowest musical sound. Below that number, the pulsations, being distinctly heard, form no musical sound, only noise. The highest musical sound which our ears are capable of receiving requires about forty thousand pulsations in a second. Above that number a shrill noise or whistle is the result. Now, if we take the seven notes of any diatonic scale we shall find that the number of pulsations producing the seventh note, counting upwards, is all but double the number required to produce the lowest or first note. ”

“ The pulse varies; in some it is full and laboring, in others quick and jerking; the head, face, and neck are livid and congested; the carotid pulsation is very perceptible; the pupils, at first contracted, dilate widely before death. ”

“ The intensity of sound depends not only upon the density and elasticity of [119] the air whose pulsation is an antecedent condition, but also upon the density and elasticity of the air through which the pulse is transmitted. While it is true that a pulse given to the denser column or stratum of air may be transmitted through a rarer medium with greater resultant force than if its origin and direction were reversed, it by no means follows that the intensity of sound is unaffected by the density of the air in which it is heard. ”

“ Hence we may conceive, that a very complex set of vibrations, arising from the mixture and combinations of degree, kind, place, and line of direction, exists always in the medullary substance, being kept up by its heat, and the pulsation of its arteries, when other causes are wanting, almost in the same manner as in a concert of music the air is agitated by vibrations of a very complex kind. ”

“ If no actual disorganization should happen, a drunken person might live until his pulse beat this number of times; but by the constant stimulus of ardent spirits, or by pulse-quickening food, or tobacco, the pulse becomes greatly accelerated, and the two billion five hundred and seventy-four million four hundred and forty thousand pulsations are performed in little more than half the ordinary term of human life, and life goes out in forty or forty-five years, instead of seventy. ”

“ It may trouble us for a moment to see why a recurrent pulsation should arise from a constantly present stimulus, but long ago Romanes discovered that a weak constantly present stimulus, such as a faradaic current of electricity, will cause rhythmical pulsation, the jellyfish responding to it periodically and regularly. ”

“ We can hear beats only up to fifteen in a second, beyond that number they give the [Pg 10] sensation of a musical or continuous sound. In our sense of sight we can see pulsations or intermittent flashes up to only six in a second, beyond that number they give the sensation of a continuous light; a gas jet, if extinguished and relit six times in a second, can be seen to flicker, but beyond that rate is to our sense of sight a steady flame. ”

“ The first, and the most decisive, is the absolute stoppage of the heart's pulsations, noted for a duration of at least five minutes, not by the touch, but by the ear. "Death is certain," says the reporter of the commission named in 1848, by the Academy of Sciences, to award the prize of competition as to the signs of true death, "when positive cessation of pulsations of the heart in the subject has been ascertained, which is immediately followed, if it has not been preceded, by cessation of respiration, and of the functions of sensation and motion." ”

“ As the waves of sound, propagated through a uniform medium, travel with uniform velocity, it follows that, when the pulsations transmitted to the first jet from the organ-pipe, and the pulsations transmitted to the second jet from the resonance-sphere, pass through equal lengths of air, they will be reflected from the revolving-mirror as coincident serrations. ”

“ It is a common observation, that persons in good health have about 75 pulsations at the wrist in a minute, consequently in 75 pulsations sound flies about 13 land miles, or 111⁄7 sea miles, which is about 1 land mile in 6 pulsations, and 1 sea mile in 7 pulses, or a league in 20 pulses. ”

“ The lips, vibrating as the breath passes through the aperture between them, communicate pulsations or series of intermittent shocks to the thin stream of air, known as the exciting current, which, issuing from them, strikes the column of air in the tube, already in a state of stationary vibration.9 The effect of this series of shocks, without which there can be no sound, upon the column of air confined within the walls of the tube is to produce sound-waves, travelling longitudinally through the tube. ”

“ The light and the heat waves of the ether are infinitesimal ripples as compared to the backward and forward pulsations that constitute the sound waves of the air. Within a space of one inch there are sixty-six thousand of the violet waves of light, which are the shortest etheric vibrations to which the human eye responds, and over thirty thousand of the red waves, the longest that affect the eye ”

“ If no watch is to be had the time is obtained by counting the pulsations of an artery. A sound pulse averages from 75 to 80 in a minute. Distances may even be guessed by observing that in clear weather the windows of a house can be counted at 4000yds. ”

“ There is a close connection between the temperature and the pulse, both of which guide the judgment in matters of health. The pulse is most rapid at birth, and becomes constantly slower until old age, ranging from a maximum at the beginning of 130 to 150 pulsations a minute to a minimum at the end of life of 50 to 65 pulsations. The average pulse through the period of adult life is from 70 to 75 beats per minute. It is considered that every rise of temperature of one degree above normal corresponds with an increase of ten beats of the pulse per minute. ”

“ A very troublesome complication of pulsations in growth, arises at high temperatures, which render further record extremely difficult. Growth is undoubtedly a pulsatory phenomenon; but under favourable circumstances, these merge practically into a continuous average rate of elongation. At a high temperature the effect of certain disturbing factors comes into prominence. ”

“ Before I answer that question, I must explain the supposed nature of those vibrations of the air, upon which sound depends; you will then readily perceive why one species of matter should be better calculated than another for exciting them. It is generally believed that sound is conveyed through air by a succession of pulsations similar to those which are occasioned on the surface of smooth water by throwing a pebble into it. ”

“ It will be seen that the star works the tap of subatomic energy just as an engine works the valve admitting heat into its cylinder; so that the pulsations of a star are started up like the pulsations of an engine. ”

“ The pulse that suggests the running of a partridge is called delirium pulse. An irregular pulse indicates delirium tremens, and a pulse which is almost imperceptible, depressed, irregular, and extremely languid, is a precursor of death. Pulsations in one suffering from fever or amorous passions are quick, and in a healthy man they are of a medium strength and perfectly regular. The capriciousness of the pulse produces other modifications very curiously described. ”

“ Take here an addendum Secondly in sitting up in bed, or changing the horizontal to a perpendicular posture, the quickness of the weak pulse is liable immediately to increase 10 or 20 pulsations in a minute, which does not I believe occur in the strong pulse, when the patient has rested himself after the exertion of rising. ”

“ The same kind of waves are produced in the air by the motion of a sonorous body, which will of course be in the centre, and the waves or pulsations will diminish in strength as they recede from that centre, until at last they become too weak to produce any effect on the ear. ”

“ On that paper the never-resting heart of the earth is now tracing, in telegraphic symbols which will one day be interpreted, a record of its pulsations and its flutterings, as well as of that slow but mighty working which warns us that we must not suppose that the inner history of our planet is ended. ”

“ All agitation is vibration. All force manifests itself in this way.
The painful brilliancy of the sun is produced by the rapid vibrations of the rays; the twinkle of the distant star, the waves of the ocean when ruffled by the winds; the shimmer of the moon on its crested surface; the brain in thinking; the mouth in talking; the beating of the heart; all, alike, obey the one grand and universal law of vibratory motion.
Qualities of Sound.—Sound is nothing but a succession of vibrations of greater or less magnitude. Pitch is produced by the number of vibrap. 157tions; intensity by their force ”

“ The pulse is more frequent when one stands than when one sits, or lies down, and this is especially so in states of debility. The taking of food, especially hot food, increases it. By placing tambours on, say, the carotid and radial arteries and recording the two pulses synchronously, it has been found that the pulse occurs later, the further the seat of observation is from the heart. The velocity with which the pulse wave travels down the arteries has been determined thus. ”

“ Nature of Sound Waves.—If some sonorous body, as a bell, be struck, it is given a quivering, or vibratory, motion. This is not confined to the bell, but is imparted to the air and other substances with which the bell comes in contact. These take up the movements and pass them to objects more remote, and they in turn give them to others, until a very considerable distance is reached. Such progressive vibrations are known as waves, and, since they act as stimuli to the organs of hearing, they are called sound waves. ”

“ But when the process is reversed, and we deduce effects from only one among concurrent and conflicting causes, theory is confounded by discordant facts. Theories of sound in purely elastic air might give results approximately realized in practice, if the actual pulses with which we are concerned were given by a flail; but are pregnant of error when the atmosphere is mixed with vicious vapors, and the pulse is a breath of air. ”

“ Again, the principal part in the human body, namely, the heart, is in constant motion, and is the source of every motion noticed in the body: it rules over the other members, and communicates to them through its own pulsations the force required for their functions. The outermost sphere by its motion rules in a similar way over all other parts of the universe, and supplies all things with their special properties. Every motion in the universe has thus its origin in the motion of that sphere: and the soul of every animated being derives its origin from the soul of that same sphere. ”

“ The box has two pipes connected with it, by means of which it can be filled with carbonic acid gas.
Provided with this apparatus, it is now possible to show you a series of experiments which will leave no doubt in your minds that the external agency which creates in us the sensation of sound is a wave-motion in the air we breathe. Let me, in the first place, show you that a sound-beam can be reflected. We adjust our sensitive flame and set the whistle in action, and create, as described, by the lens, a beam of sound. ”

“ If we could see the particles of the air in the concert-room, and fasten our attention upon any one of them, we should see it executing a most complicated motion under the combined action of these air-wave-producing instruments. We should be fascinated by the amazing dance of molecules to and fro and from side to side, as the medley of waves of compression or rarefaction embraced them and drove them hither and thither in their resistless grasp. ”