Evening star. [volume] (Washington, D.C.) 1854-1972, 1891-05-01

A Series of Lectures Illustrated by Exceed
ingIy Interesting Experiments.

illustrated
ingIy Interesting Experiments.
Wednesday at the Catholic University Rev.
John A Zahm, c. S. c., professor of physics in
the University of Notre Dame, delivered his
fifth lecture on the Philosophy of Musical
Sounds" Subjects so thoroughly scientific are
not usually considered as good drawing cards
for popular lecture course, but in the present
course the lecturer has met with most fatter-
ing success. having had crowded audiencesiat
every lecture. Beginning with the production
and transmission Of sound the course has en-
braced a thorough explanation of nearly
every phenomenon in the domain of
acoustics. In scarcely any other branch
Of the physical sciences has such pro-
gress been made in the department
of acoustics, and, strange as it may seem, nearly
all the success of scientific research in this field
has been due to the wonderful inventive genius
Of two men. Helmholtz and KONG. Indeed,
only through their work has music as q science
been rendered possible. Father Zahm brought
with him for this occasion a complete collec-
ton of physical apparatus. probably the most
complete cabinet Of acoustic apparatus in this
country. by means of which be has been enabled
to perform a series of most delicate expert
ments; and while many Of them have excited
the deepest interest among the scientific por-
ton Of the audience, all have proved both in
scientific Of his hearers.
TO SEE AND HEAR SOUND.
Probably the most striking feature Of our
recent methods Of scientific teaching is the
successful introduction Of ingenious mechan-
ical contrivances to furnish tangible iliustra-
tons OF the hidden operations of natures
forces. Nothing enables MS to grasp an idea
so quickly as to present it, as il were to the
physical eye. And by means Of some Of the
most recent triumphs of the mechanician's art
Father Zahm has found it possible during the
present course to allow his audience almost to
zee as we'll as to hear sound. Tuning forks
thrown into intensely rapid vibrations by
electro-magnets were made to trace out their
peculiar curves on smoked glass plates, thus
showing at glance the relative rapidity of
their vibrations. To every fork there belonged
not only particular musical note, but also
particular mathematical curve By means of the
wave syren, circular brass plate, whose edge
was scalloped out into o certain geometric
curve, was made to produce the note CORE
spending to that curve, and by combining sew
eral simple curves into o single more intricate
one the syren produced the same sound as the
combined notes of the forks corresponding to
the component curves.
With KONG manometric flame and revolv-
ing mirror serrated bands Of flame were pro-
duced, each band corresponding to its own
particular note. Thus the experienced eye
could, by observing the characteristic band of
light IN the rotating mirror, discover the pitch.
and, to some extent, even the intensity, of
note sung into the mouthpiece connected with
the manometric flame, hut at such a distance
away that the voice Of the singer would be in
audible.
CONFUSED NOISES SEPARATED INTO MUSICAL
TONES.
With Heimhoitzs resonator it was found
possible to analyze the most complex sounds
and to separate confused noises into pure mu-
steal notes. But the most striking proof Of the
existence OF the purest tones of the noisy hum
that We constantly hear around US was fur
nished by the melodiaphone By means Of this
simple instrument the lecturer showed the
actual possibility Of hearing q melody that did
not exist by means of an instrument that emits
no sound Scarcely less odd than this was one
OF the facts demonstrated in the lecture on
Interference OF sound" When sound pro-
ceeds from two different sources at the same time
we should expect. and as n matter Of fact we
usually do find it SO. that the two sounds would
strengthen one another. But by such an ar
rangement Of tuning forks that waves Of con-
densation proceeding from one source met
waves Of rarefaction proceeding from another,
two simultaneously produced sounds were made
to cause perfect silence. Wednesdays lecture
on Beats and Beat Tones" was Of especial in
terest to scientists, since the experiments din
proved the theory advanced by Helmholtz and
defended by Tyndal to account for the So
called resultant tones. The subject Of the lee
ture this afternoon-the concluding one OF the
course-will be The Quality Of sound" and
viii undoubtedly be fully as interesting a. any
that have preceded.