Lexington weekly intelligencer. (Lexington, Mo.) 1871-1887, 1879-09-06

work have been met by citizens OF st.
Louis, and Prot. Nipher makes himself
responsible for any deficit that may oc-
cur. 1t was begun, in connection with
the weather service, in the interest OF
the university as well as of the state.
and its chief is Jealous, industrious and
capable. There are eighty stations for
the weather service in the state.
The survey Is also made as contri-
button to science. As we said above, it
will be of value to surveyors, and it will
also be of service in the construction OF
sailing charts, as careful determine
ton of the earth's magnetism on land
aids in obtaining reliable values for the
ocean. Very little OF this work had
been done in the Mississippi valley prior
to 1878, and the coast survey charts OF
the magnetic variation are given as ap-
proxlmate in this region. Professor
Nipher finds that these estimates will re-
quire radical changes.
The determinations made in this sur
vey are: 1. The magnetic variation or
declination. 2. The intensity of mag
netlsm. 5. The dip of the needle.
The variation of the magnetic needle
is the angle between the direction of the
magnetic needle and true north and
south line. For the determination of
this angle observations must be made
upon a magnetic needle, for the mag
netic meridian, and upon the sun and
stars for the true meridian. The needle
used by Prof. Nipher is hollow cylin-
der OF steel, about three-eighths OF an
inch in diameter, in one extremity OF
which is fixed scale, the divisions of
which amount to about two minutes,
which can be read to tenths. This ena-
bles the position OF tho magnet to be
read to quarters of a minute. This mag
netic needle is hung on slender fibre OF
unspun silk. about IL inches long, and
80 small that it takes careful looking to
see it. The scale is read by the tele-
scope of an engineers transit. This tel
escope is first turned on some distant
mark "a splre) and the horizontal circle
is set on zero. This mark thus becomes
the zero point in estimating angles.
The telescope is then turned on the axis
OF the magnet about o'clock IN the
morning, and the angle through which
the telescope has been turned is meas
ured. The north pole of the needle
generally moves to the east until about
z: 80 or o'clock, and then recedes to
the west, reaching its western elonga-
ton at 80 or o'clock in the after
noon. The telescope IS kept turned on
the axis constantly, and the circle read
ings taken. In this way the mean po-
sition of the magnet is found. The daily
| swing OF the needle is from six to ten
minutes.
At night the telescope is turned on the
north star, and the circle reading of the
star is taken when it has reached the
eastern part of the apparent orbit around
the pole. This occurs little after
o'clock at this time of year. In this
latitude the telescope is then pointing
1 degree and AZ minutes east of north
This establishes the direction OF true
north, The angle between true nortt
and magnetic north is thus determined
In this city observations were made en-
tlrely Independently, at the open square
north of the third ward school ,and in thu
yard OF the Methodist Female College
The values for these two places were,
degrees. 55.1 minutes; and 8 degrees
IS 9 minutes.
A line passing little west of low
City to near st. Joseph. then bending
abruptly eastward to near Lexington
then southwest to points little west o
Holden and Vlnlta, I. T., connect
points where the magnetic needle point
9 degrees east of north. To the east thi
angle diminishes until line passing
near Cleveland. o., southwark near Ra
leigh. N. C.,is reached. Here the needl
points north. Further to the cas-
| the needle points west OF north. the an
gle increasing as you go further east. L
Missouri the angle of variation is dimin
ishing at the rate of about minutes
year.
The intensity OF magnetism is deter
mined by the time of oscillation OF tn
magnetic needle. Its suspension on th
silk fibre is so delicate that the heav
needle, weighing several ounces, will
continue in vibration for several hours
The time of vibration is determined az
curately, Professor Nlpher says to tn
thousandth of a second, though thi
seems almost Incredible. At place
where the magnetic force is strong, th
time OF vibration is corresponding
shorter. The values directly observe
are corrected, so carefully is every mil
utie of this survey made, for the effe,
due to the twist developed in the sill
fibre during the oscillation, for vari,
tions in temperature (Which change
> the strength of the magnet, and for tt
gradual loss in strength of the magne
due to the jar of trains, &c. The
corrections are too complex to admit
treatment here.
The two determinations of intensi
made at this place. at the points me-
toned, were 4.702S and 4.7O21. IT.
difference between these determinatio
is only one hundredth OF one per cer
of the quantity observed.
AS is well known, compass need
lies horizontal. This is because t
south end is made heavier. If neeG
is first accurately balanced, and tn
magnetized, the north end is found
dip below the horizontal. 10 det,