Copyright
D. S. (David Samuel) Margoliouth.

The Popular science monthly (Volume 19) online

. (page 25 of 110)
Online LibraryD. S. (David Samuel) MargoliouthThe Popular science monthly (Volume 19) → online text (page 25 of 110)
Font size
QR-code for this ebook


a hearing-tube. The beam of light is interrupted by its passage through
the two slotted disks shown at B, and in operating the instrument mu-
sical signals like the dots and dashes of the Morse alphabet are pro-
duced from the sensitive receiver (A) by slight motions of the mirror
(C) about its axis (D).

In place of the parabolic reflector shown in the figure a conical
reflector like that recommended by Professor Sylvanus Thompson * can
be used, in which case a cylindrical glass vessel would be preferable to
the flask (A) shown in the figure.

In regard to the sensitive materials that can be employed, our
experiments indicate that in the case of solids the physical condition
and the color are two conditions that markedly influence the intensity
of the sonorous effects. The loudest sounds are produced from sub-
stances in a loose, 2)orous, spongy condition, and from those that have
the darkest or most absorbent colors.

The materials from which the best effects have been produced are
cotton-wool, worsted, fibrous materials generally, cork, sponge, plati-
num, and other metals in a spongy condition, and lampblack.

The loud sounds produced from such substances may perhaps be
explained in the following manner : Let us consider, for example, the
case of lampblack — a substance which becomes heated by exposure
to rays of all refrangibility. I look upon a mass of this substance as
a sort of sponge, with its pores filled with air instead of water. When
a beam of sunlight falls upon this mass, the particles of lampblack
are heated, and consequently expand, causing a contraction of the air-
spaces or pores among them.

Under these circumstances a pulse of air should be expelled, just
as we would squeeze out water from a sponge.

The force with which the air is expelled must be greatly increased
by the expansion of the air itself, due to contact with the heated par-
ticles of lampblack. When the light is cut off, the converse process
takes place. The lampblack particles cool and contract, thus enlarg-
ing the air spaces among them, and the inclosed air also becomes cool.
Under these circumstances a partial vacuum should be formed among
the particles, and the outside air would then be absorbed, as water is
by a sponge when the pressure of the hand is removed.

I imagine that in some such manner as this a wave of condensation
is started in the atmosphere each time a beam of sunlight falls upon
lampblack, and a wave of rarefaction is originated when the light is
cut off. We can thus understand hoio it is that a substance like lamp-
black produces intense sonorous vibrations in the surrounding air,
while at the same time it communicates a very feeble vibratio7i to the
diaphragm or solid bed upon which it rests.

This curious fact was independently observed in England by Mr.
Preece, and it led him to question whether, in our experiments with
* "Philosophical Magazine," April, 1881, vol. xi, p. 286.



PRODUCTION OF SOUND BY RADIANT ENERGY. 193

thin diaphragms, the sound heard was due to the vibration of the disk
or (as Professor Hughes had suggested) to the expansion and contrac-
tion of the air in contact with the disk confined in the cavity behind the
diaphragm. In his paper read before the Royal Society on the 10th
of March, Mr. Preece describes experiments from which he claims to
have proved that the effects are wholly due to the vibrations of the
confined air, and that the disks do not vibrate at all.

I shall briefly state my reasons for disagreeing with him in this
conclusion :

1. "VVhen an intermittent beam of sunlight is focused upon a sheet of hard
rubber or other material, a musical tone can be heard, not only by placing the
ear immediately behind the part receiving the beam, but by placing it against
any portion of the sheet, even though this may be a foot or more from the place
acted upon by the light.

2. When the beam is thrown upon the diaphragm of a " Blake transmitter,"
a loud musical tone is produced by a telephone connected in the same galvanic
circuit with the carbon button (A), Fig. 4. Good effects are also produced when
the carbon button (A) forms, with the battery (B), a portion of the primary cir-
cuit of an induction-coil, the telephone (C) being placed in the secondary circuit.

In these cases the wooden box and mouth-piece of the transmitter should be
removed, so that no air-cavities may be left on either side of the diaphragm.

It is evident, therefore, that in the case of thin disks a real vibra-
tion of the diaphragm is caused by the action of the intermittent beam^
independently of any expansion and contraction of the air confined in
the cavity behind the diaphragm.

Lord Rayleigh has shown mathematically that a to-and-fro vibra-
tion, of sufficient amplitude to produce an audible sound, would result
from a periodical communication and abstraction of heat, and he says :
" AVe may conclude, I think, that there is at present no reason for dis-
carding the obvious explanation that the sounds in question are due to
the bending of the plates under unequal heating " (" Nature," vol. xxiii,
p. 274). Mr. Preece, however, seeks to prove that the sonoi'ous effects
can not be explained upon this supposition ; but his experimental proof
is inadequate to support his conclusion. Mr. Preece expected that, if
Lord Ray leigh's explanation was correct, the expansion and contraction
of a thin strip under the influence of an intermittent beam could be
caused to open and close a galvanic circuit so as to produce a musical
tone from a telephone in the circuit. But this was an inadequate way
to test the point at issue, for Lord Rayleigh has shown (" Proceedings
of the Royal Society," 1877) that an audible sound can be produced
by a vibration whose amplitude is less than a toi-milliojith of a centi-
metre, and certainly such a vibration as that would not have sufficed to
operate a " make-and-break contact" like that used by Mr. Preece.
The negative results obtained by him can not, therefore, be considered
conclusive.

The following experiments (devised by Mr. Tainter) have given re-

VOL. XIX. 13



194 THE POPULAR SCIENCE MONTHLY,




-\.



suits decidedly more favorable to the theory of Lord Rayleigh than to
that of Mr. Preece :

1. A strip (A) similar to that used in Mr. Preece's experiment was attached
firmly to the center of an iron diaphragm (B), as shown in Fig. 5, and was




PRODUCTION OF SOUND BY RADIANT ENERGY. 195

then palled taut at right angles to the plane of the diaphragm. When the inter-
mittent beam was focused upon the strip (A), a clear musical tone could be heard
by applying the ear to the hearing-tube (C).




Thu seemed to indicate a rapid expamion and contraction of the substance
under trial.

But a vibration of the diaphragm (B) would also have resulted if the thin
strip (A) had acquired a to-and-fro motion, due either to the direct impact of
the beam or to the sudden expansion of the air in contact with the strip,

2. To test whether this had been the case, an additional strip (D) was attached
by its central point only to the strip under trial, and was then submitted to the
action of the beam, as shown in Fig. 6.

It was presumed that, if the vibration of the diaphragm (B) had been due to
a. pushing force acting on the strip (A), the addition of the strip (D) would not
interfere with the effect ; but, if, on the other hand, it had been due to the longi-




tudinal expansion and contraction of the strip (A), the sound would cease, or at
least be reduced. The beam of light falling upon the strip (D) was now inter-
rupted as before by the rapid rotation of a perforated disk, which was allowed
to come gradually to rest.

No sound waa heard excepting at a certain speed of rotation, when a feeble
musical tone became audible.



196 THE POPULAR SCIEXCE MONTHLY.

This result is confirmatory of the first.

The audibility of the effect at a particular rate of interruption sug-
gests the explanation that the strip D had a normal rate of vibration
of its own.

When the frequency of the interruption of the light corresponded
to this, the strip was probably thrown into vibration after the manner
of a tuning-fork, in which case a to-and-fro vibration would be propa-
gated down its stem or central support to the strip (A).

This indirectly proves the value of the experiment.

The list of solid substances that have been submitted to experiment
in my laboratory is too long to be quoted here, and I shall merely say
that we have not yet found one solid body that has failed to become
sonorous under proper conditions of experiment.*

Experiments with Liquids. — The sounds produced by liquids are
much more difficult to observe than those produced by solids. The
high absorptive power possessed by most liquids would lead one to
expect intense vibrations from the action of intermittent light ; but
the number of sonorous liquids that have so far been found is ex-
tremely limited, and the sounds produced are so feeble as to be heard
only by the greatest attention and under the best circumstances of
experiment. In the experiments made in my laboratory, a very long
test-tube was filled with the liquid under examination, and a flexible
rubber tube was slipped over the mouth far enough down to prevent the
possibility of any light reaching the vapor above the surface. Pre-
cautions were also taken to prevent reflection from the bottom of the
test-tube. An intermittent beam of sunlight was then focused upon
the liquid in the middle portion of the test-tube by means of a lens of
large diameter.

RESULTS.

Clear water No sound audible.

"Water discolored by ink Feeble sound.

Mercury No sound heard.

Sulphuric ether * Feeble but distinct sound.

Ammonia " " " ''

Ammonio-sulphate of copper " "

Writing-ink '* "

Indigo in sulphuric acid " " " "

Chloride of copper * " " " "

The liquids distinguished by an asterisk gave the best sounds.

Acoustic vibrations are always much enfeebled in passing from
liquids to gases, and it is probable that a form of experiment may be
devised which will yield better results by communicating the vibra-
tions of the liquid to the ear through the medium of a solid rod.

* Carbon and thin microscope-glass are mentioned in my Boston paper as non-
responsive, and powdered chlorate of potash in the communication to the French Acad-
emy (" Comptes Rendus," vol. csl, p. 593). All these substances have since yielded
Bounds under more careful conditions of experiment.



COMPOUND POLITICAL HEADS. 197

Experiments with Gaseous Matter. — On the 29tli of November,
1880, 1 had the pleasure of showing to Professor Tyndall, in the labora-
tory of the Royal Institution, the experiments described in the letter
to Mr. Taiuter from which I have quoted above ; and Professor Tyn-
dall at once expressed the opinion that the sounds were due to rapid
changes of temperature in the body submitted to the action of the
beam. Finding that no experiments had been made at that time to
test the sonorous properties of different gases, he suggested filling one
test-tube with the vapor of sulphuric ether (a good absorbent of heat),
and another with the vapor of bisulphide of carbon (a poor absorbent),
and he predicted that if any sound were heard it would be louder in the
former case than in the latter.

The experiment was immediately made, and the result verified the
prediction.

Since the publication of the memoirs of Rontgen * and Tyndall f
we have repeated these experiments, and have extended the inquiry
to a number of other gaseous bodies, obtaining in every case similar
results to those noted in the memoirs referred to.

The vapors of the following substances were found to be highly
sonorous in the intermittent beam : Water-vapor, coal-gas, sulphuric
ether, alcohol, ammonia, amylene, ethyl bromide, diethylamene, mer-
cury, iodine, and peroxide of nitrogen. The loudest sounds were ob-
tained from iodine and peroxide of nitrogen.

I have now shown that sounds are produced by the direct action
of intermittent sunlight from substances in every physical condition
(solid, liquid, and gaseous), and the probability is, therefore, very
greatly increased that sonorousness under such circumstances will be
found to be a universal property of matter.
[To he continued.]



THE DEYELOPMEXT OF POLITICAL IXSTITUTIONS.

Bt HERBERT SPENCER.
VII. — COMPOUND POLITICAL HEADS.

IX the preceding chapter on chiefs and kings, we traced the develop-
ment of the first element in that triune political structure which
everywhere shows itself at the outset. We pass now to the develop-
ment of the second element — the group of leading men among whom
the chief is, at first, merely the most conspicuous. Lender what con-
ditions this so evolves as to subordinate the other two, what causes

* " Annalen der Thysik unci Chemie," 1881, No. 1, p. 155.
t " Proceedings of the Royal Society," vol. xxxi, p. 307.



198 THE POPULAR SCIENCE MONTHLY.

make it narrower, and what causes widen it until it passes into the
third, we have here to observe.

If the innate feelings and aptitudes of a race have large shares in
determining the size and cohesions of the social groups it forms, still
more must they have large shares in determining the relations which
arise among the members of such groups. While the mode of life
followed tends to generate this or that political structure, its effects
are always complicated by the effects of inherited character. Whether
or not the primitive state, in which governing power is equally dis-
tributed among all warriors or all elders, passes into the state in which
governing power is monopolized by one, depends, in part, on the life of
the group as predatory or peaceful, and in part on the natures of its
members as prompting them to oppose dictation more or less doggedly.
A few facts M-ill make this clear.

The Araf uras (Papuan-Islanders) who " live in peace and brotherly
love," have no other " authority among them than the decisions of
their elders." Among the harmless Todas "all disputes and questions
of right and wrong are settled either by arbitration or by a Puncha-
yet — i. e., a council of five." Of the Bodo and Dhimals, described as
averse to military service, and " totally free from arrogance, revenge,
cruelty, and^er^c," we read that though each of their small communi-
ties has a nominal head who pays the tribute on its behalf, yet he is
without power, and " disputes are settled among themselves by juries
of elders." In these cases, besides absence of the causes which bring
about chiefly supremacy, may be noted the presence of causes which
directly hinder it. The Papuans generally, typified by the Arafuras
above named, while they are described by Modera, Ross, and Kolff, as
"good-natured," "of a mild disposition," kind and peaceful to stran-
gers, are said by Earl to be unfit for military action ; " their impatience
of control . . . utterly precludes that organization which would en-
able "the Papuans "to stand their ground against encroachments."
The Bodo and Dhimals while " they are void of all violence toward
their own people or toward their neighbors," also " resist injunctions,
injudiciously urged, with dogged obstinacy." And of a kindred " very
fascinating people," the Lepchas, amiable, peaceful, kind, as travelers
unite in describing them, and who will not take service as soldiers,
we are told that they will " undergo great privation rather than sub-
mit to oppression or injustice."

Where the innate tendency to resist coercion is strong, we find
this uncentralized political organization maintained, notwithstanding
the warlike activities which tend to initiate settled chieftainship. The
Nagas " acknowledge no king among themselves, and deride the idea
of such a personage among others " ; their " villages are continually
at feud" ; "every man being his own master, his passions and inclina-
tions are ruled by his share of brute force." And then we further
find that " petty disputes and disagreements about property are settled



COMPOUND POLITICAL HEADS. 199

by a council of elders, tlie litigants voluntarily submitting to their
arbitration. But, correctly speaking, there is not the shadow of a con-
stituted authority in the Naga community, and, wonderful as it may
seem, this want of government does not lead to any marked degree of
anarchy and confusion." Similarly among such peoples, remote in type,
as many of the warlike tribes of North America. Speaking of these
Indians in general, Schoolcraft says that "they all wish to govern,
and not to be governed. Every Indian thinks he has a right to do as
he pleases, and that no one is better than himself ; and he will fight
before he will give up what he thinks right." Of the Comanches, as
an example, he remarks that " the democratic principle is strongly im-
planted in them"; and that for governmental purposes "public coun-
cils are held at regular intervals during the year." Further, we read
that in districts of ancient Central America there existed somewhat
more advanced societies which, though warlike, were impelled by a
kindred jealousy to provide against monopoly of power. The govern-
ment was by an elective council of old men who appointed a war-
chief ; and this war-chief, " if suspected of plotting against the safety
of the commonwealth, or for the purpose of securing supreme power
in his own hands, was rigorously put to death by the council."

Though the specialities of character which thus lead certain kinds
of men in early stages to originate compound political headships, and
to resist, even under the stress of war, the rise of single political head-
ships, are innate, we are not without clews to the circumstances which
have made them innate ; and, with a view to interpretations presently
to be made, it will be useful to glance at these. The Comanches and
kindred tribes, roaming about in small bands, active and skillful horse-
men, have, through long-past periods, been so conditioned as to make
coercion of one man by another diiRcult. So, too, has it been, though
in another way, with the Nagas. " They inhabit a rough and intri-
cate mountain-range"; and their villages are perched "on the crests
of ridges." Again, very significant evidence is furnished by an inci-
dental remark of Captain Burton to the effect that in Africa, as in Asia,
there are three distinctly marked forms of government — military des-
potisms, feudal monarchies, and rude republics ; the rude republics
being those formed by " the Bedouin tribes, the hill people, and the
jungle races." Clearly, the names of these last show that they inhabit
regions which, hindering by their physical characters a centralized
form of government, favor a more diffused form of government, and
the less decided political subordination which is its concomitant.

These facts are obviously related to certain other facts with which
they must be joined. Already evidence has been given that it is rela-
tively easy to form a large society if the country is one within which
all parts are readily accessible, while it has barriers through which
exit is difficult ; and that, conversely, formation of a large society is
prevented, or greatly delayed, by difficulties of communication within



zoo THE POPULAR SCIENCE MONTHLY.

the occupied area, and by facilities of escape from it. But, as we
now see, not only is political integration under its primary aspect of
increasing mass hindered by these last-named physical conditions, but
there is hindrance to the development of a more integrated form of
government. That which impedes social consolidation also impedes
the concentration of political power.

The truth here chiefly concerning us, however, is that the contin-
ued presence of the one or the other set of conditions fosters a char-
acter to which either the centralized or the diffused kind of political
organization is appropriate. Existence, generation after generation,
in a region where despotic control has arisen, produces an adapted
type of nature ; partly by daily habit and partly by survival of those
most fit for living under such control. Contrariwise, in a region
favoring maintenance of their independence by small groups, there is
a strengthening, through successive ages, of sentiments averse to re-
straint ; since not only are these sentiments exercised in all by resist-
ing the efforts from time to time made to subordinate them, but, on
the average, those who most pertinaciously resist are those who, re-
maining unsubdued, and transmitting their characters to posterity,
determine the tribal character.

Having thus glanced at the effects of the factors, external and in-
ternal, as displayed in simple tribes, we shall understand how they
cooperate when, by migration or otherwise, such tribes fall into cir-
cumstances which favor the growth of large societies.

The case of an uncivilized people of the nature described, who
have in recent times shown what occurs when union of small groups
into great ones is prompted, will best initiate the interpretation.

The Iroquois nations, each made up of many tribes previously
hostile, had to defend themselves against European invaders. Com-
bination for this purpose among these five (and finally six) nations
necessitated a recognition of equality of power among them ; since
agreement to join would not have been arrived at had it been required
that some divisions should be subject to others. The groups had to
cooperate on the understanding that their " rights, privileges, and
obligations " should be the same. Though the numbers of permanent
and hereditary sachems appointed by the respective nations to form
the Great Council, differed, yet the voices of the several nations were
equal. Omitting details of the organization, we have to note first,
that for many generations, notwithstanding the wars which this
league carried on, its constitution remained stable — no supreme indi-
vidual arose ; and, second, that this equality of power among the
groups coexisted with inequality within each group : the people had
no share in its government.

A clew is thus furnished to the genesis of those compound head-
ships with which ancient history familiarizes us. We are enabled to



COMPOUND POLITICAL HEADS. 201

see how there came, to coexist, in the same societies, some institutions
of a despotic kind, with other institutions of a kind appearing to be
based on the principle of equality, and often confounded with free
institutions. Let us recall the antecedents of those early European
peoples who developed governments of this form.

During the wandering pastoral life, subordination to a single head,
growing naturally out of fatherhood, was fostered. A recalcitrant
member of any group had either to submit to the authority under
which he had grown up, or, throwing off its yoke, had to leav^ the
group and face those risks which unprotected life in the desert threat-
ened. The establishment of this subordination was furthered by the
more frequent survival of groups in which it was greatest ; since, in
the conflicts between groups, those of which the members were in-
subordinate, ordinarily being both smaller and less able to cooperate
effectually, were the more likely to disappear. But now, to the fact
that in such families and clans circumstances fostered obedience to
the father and to the patriarch, has to be added the fact above em-
phasized, that circumstances also fostered the sentiment of liberty in
the relations between clans. The exercise of power by one of them
over another was made difficult by wide scattering and by great mo-
bility ; and with successful opposition to external coercion, or evasion
of it, carried on through numberless generations, the tendency to re-
sent and resist all strange authority was likely to become strong.

Whether, when groups thus disciplined aggregate, they assume
this or that form of political organization, depends partly, as already
implied, on the conditions into which they fall. Even could we omit
those differences between Mongols, Semites, and Aryans, established
in prehistoric times by causes unknown to us — even had complete
likeness of nature been produced in them by long continuance of pas-
toral life — yet large societies, formed by combinations of these small
ones, could be similar in type only under similar circumstances.
Hence, probably, the reason why Mongols and Semites, where they
have settled and multiplied, have failed to maintain the autonomies of
their hordes after combination of them, and to evolve the i-esulting
institutions. Even the Aryans, among whom chiefly the less concen-



Online LibraryD. S. (David Samuel) MargoliouthThe Popular science monthly (Volume 19) → online text (page 25 of 110)