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Page 8
The instrument works best when the chariots, A and B, are about
opposite to each other; when they are at opposite extremities of f f
and f' f' respectively, the pull at P tends to produce a skewing
couple. If the chariot, B, could be put upon f f and work, if needful,
by a double parallelogram from m m, we should have, excepting the skew
pull, some great practical advantages. We might throw the whole of the
weight of the machine on the one pair of friction wheels, and replace
the other pair by a single wheel, the portion q' f' f' q' of the
machine virtually disappearing. Three wheels, of course, would be a
real improvement. Further, we should have the sum curve and primitive
drawn to the same base line, and the simplification in the number of
parts ought largely to reduce the cost of the instrument.
To be able to perform "inverse summation" (which in the language of
differential calculus is to find y as a function of x, when we are
given y=f(dy/dx), and not dy/dx=f(x) as usual), we only want a means
of making the plane of the wheel, w, parallel instead of perpendicular
to m' m', and it is easy to design a modification in the construction
which will allow of this change.
I hope the above description of the integraph may have made its
construction and method of working sufficiently clear. Those of you
who have a taste for mechanical work, and the necessary tools, might,
I think, with some patience, construct a workable integraph. I expect
the pivots would be the hardest part of the work. I hope, some day,
myself to have another instrument made with a more readily changeable
polar distance, with trace and guide points working in the same
vertical, and a wheel permitting of inverse summation. If this project
is ever carried out, I hope I may be permitted to communicate further
particulars to our society.
* * * * *
After some forty years of immersion in the waters of the pool of
Echoschacht, not far from Hermannstadt, several human bodies have been
brought to the surface in a state of perfect preservation.
* * * * *
SOME HINTS ON SPIKING TRACK.
The usual dimensions of track spikes are 51/2 X 9.16 inches square,
their weight about half a pound each. Their common defects are
brittleness and imperfect points. In spiking track, the most important
points to be attended to are the proper spacing of the ties and
driving the spikes in such a manner that the ties shall be held in
place at right angles to the track and the rails in true gauge; to
insure the latter, the track gauge should always be used when spiking
the gauge side, the rail being held to proper position by a lining
bar. The gauge should be kept about 6 or 8 in. ahead of the tie being
spiked and should not be lifted until the spikes are driven home;
gauges should be tested regularly and every morning when they are to
be used all day, so as to insure a true gauge all the time. The two
inner spikes should be set on one side of the tie and the two outer
spikes on the other, as indicated in the accompanying sketch. This
prevents the tie from slewing around, and thus deranging the gauge of
the track, as well as interfering with the proper spacing of the ties.
The joints and centers should be spiked first, which will bring the
rails to their proper position on the ties, which in turn will assist
intermediate spiking. Each tie should be carefully gauged as spiked
and, as before indicated, the ties with the broadest faces being
selected for the joints.
In gauging ties it is very convenient to have measured off on the
handles of the mauls in the hands of the forward spikers the distance
from the outside of the rail to the end of the tie. This distance will
then be gauged on the tie, when it will be lifted to the rail and
securely spiked; the gauge is then used, and the loose rail held in
place with the lining bar as previously indicated, loose gauge being
given on curves, in accordance with directions of the engineer, the
allowance for which is about 1/8 in. on a 2� curve, up to about 3/4 in.
on a 12� curve.
This widening of the gauge should begin on the tangent, back of the
P.C., the full amount of excess over true gauge being reached by the
time the P.C. is reached and continue all the way around the curve,
running from the P.T. in the same manner as back of the P.C.
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