Shepherdstown register. [volume] (Shepherdstown, Va. [W. Va.]) 1849-1955, 1897-06-10

ther into space.
The great lens of the Yerkes tele-
scope has been ten years in making.
1t was a rough block in the factory of
NJ. Mantois, Paris, in 1887, says the
Chicago Times-Herald. This French
man has the only plant in the world
which can produce large disks of op-
tical glass, and he was given the COM
mission to make the lump from which
the Yerkes lens is made.
1t is not possible to tell the story of
the making of the great lump because
the man who has the monopoly keeps
his formulas secret. The lump weighed
over six hundred pounds at the be-
ginning and it was worth $4,000 as it
came from the molds in case the sub
sequent tests should prove that it was
exactly what the skilled workmen de-
signed that it should be.
The glass was dug from the sands
in which it was cast in the summer of
1887. Professor Alvin Clark, of Cam
bridge, Mass, went across the ocean
and took temporary possession OF the
great mass. 1t was not to be accepted
unless it should prove able to stand
all the tests which the greatest tele-
scope maker in the New World should
apply to it. The glass was put into
condition for the series Of trials and
Professor Clark worked over it.
Months were spent in cutting, bak-
ing and molding it. The processes
grew more exacting at each stage, and
Mantois and the professor stood with
bated breath while the big lump was
taken from the furnaces. They both
knew that a minute might destroy
hope, or the profit of the year. 1t is
the record of this singular factory that
many great lens stands all the pre-
liminary work and then breaks at the
last test
The glass did not reach the Clark
workshop, near Boston, until three
years after it was cast. There were
two years in which little actual work
was done upon it, the work being
mostly experimental and designed to
contrive means for handling the big
lens. Professor Clark began actively
on it in 1892, and there has not been
day since that the glass has not been
on his mind. He gave it five years Of
ceaseless, constant care-worry that
the work might cost him his reputa-
ton
Professor Clark says there is moth
ing secret in his part of the work. 1t
began with a series Of tests which an
ordinary man could learn, provided
he desired to give his life to the making
of lenses. The lump was roughly pol
ished and roughly hewn to the general
form. 1t then spent year in the
grinding-room, taking graduated
course in emery. The treatment at
first was in the coarsest dust and then
dropped down to the point in which
the dust seemed nothing at all. This
course was followed by jewelers. rouge
and beeswax and the daintiest matter
known that would cause any friction,
and still not enough so that day 8
rubbing would make any impression.
The polishing machine is a special
contrivance which has the motion Of
human hand. lis necessary that the
glass underneath rests on perfectly
smooth foundation, and there are vari-
Gus means employed for making this
foundation. Professor Clark says that
the usual way is to put the glass in
dish of mercury. The Yerkes lens
was put upon automatically adjusted
pegs, the points being covered with
pitch.
1t was necessary during the process
to test the glass at frequent intervals.
An illustration Of the delicate and ac-
curate properties of the lens Is found
in the statement that the heat Of the
hand will raise a lump on the surface
which will destroy its purpose. The
machine which registers the irregulari-
ties caused by such an Insignificant
force as the heat from the hand is
called the spherometer.
From time TO time Professor Clark
took the glass from its pins, put it in
the end of tube and gazed at the
stars. This tube was sixty feet long.
Professor Clark would never tell any