Perrysburg journal. (Perrysburg, Wood Co., O. [Ohio]) 186?-1965, 1878-11-22
AMERICAN DISPLAY AT THE PARIS
EXPOSITION.
Wonders of the Mechanical Depart-
ment.
[ From the London Times, Aug. 2.l

From the London Times, Aug. q
Perhaps, however, the most I'm
portan. display in this department, all things
considered, is that of the Waltham Watch
Company, their first in the European exhibit
tions. The readers of the Times reports OF
the Philadelphia Exhibition will not need to
be informed of the admirable machinery by
which the works of the Waltham watches are
produced, or their singular eXactitude, which
enables any part of a watch to be replaced by
the corresponding piece of any other watch OF
the same grade. In this mechanical produc-
tion of machines, America has long led the
world, and the mechanism by which the En-
glish army rifle is still produced is with i'm
material notifications a contribution from
the American armories. But In the Waltham
works science has been brought to the
aid of native ingenuity to such degree that
even since the Philadelphia Exhibition the
fabrication of watches has gone through
large arc Of another revolution. What was
begun by applying such machines that their
work was beyond competition on anything
like equal terms from any hand-work is con-
tinued by the construction OF the most essen
tial parts Of watch on new principle, which
permits an approach to perfection unattain-
able by the old mechanism, however pro-
duced. Every one knows that the great diff
Guilty in making chronometers has been the
compensation for the effects Of expansion aud
contraction due to change OF temperature;
but what is less well known is that this diff
Guilty is due less TO the balance, which, by its
construction with bi-segmental rim (of brass
and steeD, may be perfectly corrected, than
to the expansion of the balance or hair
spring, which, being immensely longer, causes
five times the error caused by the expansion
or contraction balance wheel alone. The
two pieces must be considered as one,
and the compensation effected in the wheel
or lin must answer for the spring as well as
for itself. The theoretical and insuperable
difficulty in this compensation has always been
that the error caused by the expansion and
contraction OF the spring was in a different
ratio from that of the correcting expansion or
contraction wheel. and the two quantities may
be compared to curves with two Tadii, which
could be brought together at TWO points, but
not to coincide throughout, so that if the COM
pensation at the extremes OF temperature Is
correct, the mean must be in error and tfcS
UerSd
The old compensation was, speaking broad
~, in brazing band of brass on one of steel
process both theoretically and mechanically
erroneous, since the contraction and eXpan-
sion can only go on with certain tendency to
disrupture OF the elements and consequent in
equality Of the action. The new balance pro-
seeds on an entirely different arrangement Of
the cOmpensating metals. The rim, of plain
steel, is cut nearly through at the fixed ex.
tremities of the semi circles by severn,
sdw-tooth shaped notches, the number de-
tcrmined by experiment, and the brass is
forced into these notches. The compensat
luS hClkhis dIC tuCH pul Oh db blt OLltI
cXtremities of the semi-circes instead of be-
ing distributed along them empirically, and il
isfound possible in this arrangement so TO dis
tribute the compensation and compensating
weights as to give at will a compensation for
the mean temperature either in excess of, OF
less than the extremes, and of course, to give
q compensation which shall coincide through.
out, which makes it theoretically possible to
give absolute compensation for all tempera.
lures at once. 1t is difficult TO make this
clear, without diagrams showing the eXac,
curves attained by experiment; but the nature
OF the result will be appreciated by those who
know the mechanism Of the balance. 1t is
simply the theoretical elimination of all error
from the compensated balance so far as tenn
perature is concerned. Practically and me-
chanicallY there Will always be some, due to
the inherent imUerfectOn of human workman.
ship; but il is believed that the mean error, and
equally the manual adjustment required will be
reduced TO one-third of that actually obtaining
under the old form of balance. But 10 illustrate
how involved are the various improvements In
mechanism it may be noted that the delicacy Of
construction OF the new balance would only
have been possible with the mechanism intro
duced by the Waltham Company, the precision
OF which may be judged from that of the mi.
crometer last produced and shown at Paris,
which measures the twenty-tive-thousandth
part of an inch, and even indicates that so
largely that 1t might be divided under a lens
readily into hundred thousandths, A mi
cTOmeter screw gauge detects inequalities in
the thread of a screw up TO hundred thou
Sandths, and a screw made for the Govern
ment Scientific Commission to correct the
measures has been constructed in which the
maximum OF error in the thread is less than one
ten-thousandth part of an inch.