Wood County reporter. [volume] (Grand Rapids [i.e. Wisconsin Rapids], Wis.) 1857-1923, 1873-09-04

spring attached to the telescope The
second wire is reached, and again the
spring is tapped, and so on throughout
the whole of the seven or nine webs en-
ployed in the observation.
The spring is connected with tele-
graphic wire extending to a "chrono-
graph" in a distant part of the building;
and in order to understand the method of
recording the observation, we will now
follow the Geographic signal, or, as mag
nation is even switter than the telegraph,
we will imagine that we have reached the
"chronograph" first, and are there ready
to receive the signals.
Accordingly we find ourselves in a
queer little chamber, in which the most
prominent object is very beautiful speci-
men of clock whose pendulum, instead
of oscilating backwards and forwards,
swings round in circle, thus producing
motion perfectly uniform and unbroken
This clock is revolving the "chrono-
graph" which consists of a cylinder
around which a sheet of white paper has
been strained While we are watching
this revolving barrel, we see the observers
signals come. A little steel point, which
is travelling over the surface of the paper,
is in electric communication with the
and every time the observer taps the
spring, this little travelling point pricks
into the paper, thus recording that the
sun has just crossed wire" This in
itself, however, would not be record of
the time of transit if it were not that
another little steel point, which is in con-
nection with a galvanic clock in another
part of the building, has previously mark
% sheet
senting precise seconds of time On the
completion of the observation the paper
may be removed from the cylinder and
affords permanent record of it.
Nothing, perhaps, throughout the OBJ
servatory at Greenwich, is calculated to
strike the visitor with greater astonish-
ment than that galvanic clock to which
reference has just been made. There is
nothing very remarkable in its appear
ance, but the work it accomplishes renders
it perhaps the most wonderful clock in
the world, and certainly the most impor-
tant one in England.
In the first place, as we have seen, it
plays an important part in registering OBJ
servatiOns. Besides this it regulates sew
eral clocks within the Observatory, as well
as the large one already referred to out
side the gates; one at Greenwich Hospital
Schools, another at the London Bridge
Station of the South Eastern Railway,
another at the Post Office, St. Martin sic
Grand, and another in Lombard Street
Once every day it telegraphs correct
time to the great clock tower at West
minister; it drops the signal ball over the
Observatory, another near Charing Cross,
and one at Deal; it fires time guns at
Shields and Newcastle, and every hour
throughout the day it flashes out correct
time to each of the railway companies.
All this is accomplished as it We're by
the mere vOlitiOn of the clock, and with
out any human interference whatever
Every morning it is corrected by an actual
observation of a star; and thus, without
being aware of it, do we every day start
our trains, and make our appointments,
and take our meals by the motions of the
heavenly bodies as observed and recorded
during the preceding night.
We now proceed to one of those curl
Gus little domes surrounding various
parts of the Observatory Here we find
an instrl lent devoted entirely to the
study Of the moon. Observations of the
moon are of immense Importance to US
as a nation of navigatOrs, inasmuch as
she affords the means Of determining
lOu0IluuC DIT Std. lItI I1OtlOHS uO"cNtl,
from various causes, are of an extremely
complicated nature, and it is very neces-
sary that she shall be observed at all
times and under ali circumstances. But
with the transit circle, the instrument
first noticed, it is plain that the moon
could be observed only when she is cross
ing the meridian, and not always then.
Some five or six-and-twenty years ago,
therefore, Sir George Airy, the present
Astronomer Royal, designed the "Altazi-
muth," and since then the importance Of
Greenwich as lunar observatory has
been ust about doubled.
With this instrument and the transit
circle the Observatory might do all that,
strictly speaking, comes within its prov
ince. The whole duty of Greenwich, as
defined by Herschel, is ''to furnish now,
and in all future time, the best and most
perfect data by which the laws of the
lunar and planetary movements, as de
veloped by theory, can be compared with
observation" Mensurative astronomy
for practical purposes is the great bust
ness of Greenwich.
The Great Equatorial telescope was
mounted about sixteen years ago, under
the direction and from the plans of the
present Astronomer Royal. 1t is the
largest instrument in the Observatory,
and of its kind is one Of the finest in the
world. It's object glass, which is thirteen
inches in diameter, and has a focal dis
lance of eighteen feet, alone cost 81 200
The most curious feature in this telescope
is the clOckwOrk arrangement by which
it follows any object under examination.
1t is used, as already intimated, chiefly
for what may be called gazing purposes
such, for instance, as the scrutiny OF the
marvellous eruptiOnS on the surface OF the
sun, or of the mountains of the moon, ana
it is often necessary to continue such OBJ
servations for hours together. 1t is plain,
however, that # an observer is examining
the face Of the sun, the motion OF the
earth will gradually bear him and his
telescope eastward until the great lumln-
ary is lost to view He will steadily
creep out at the western side of the field.
This is obviated by the operation OF a
clock driven by falling water. This
powerful piece of mechanism is connect
ed with the great iron framework support
ing the telescope, and just as the earth
creeps round from west to east, the tele-
scope and all that pertains to 1t is borne
round from east to west. Thus, so far as
the motion of the earth is concerned, the
sun, MOON or stars as seen through the
Great Equatorial will appear to be per
tectly stationary.
We have now seen all the more proml-
nent features of Greenwich Observatory,
though there vet remain innumerable OBJ
iects of the utmost interest-rain guages,