Daily Kennebec journal. [microfilm reel] (Augusta, Me.) 1870-1975, 1913-05-15
ONE MiLLioNTH OF AN INCH.
"Most Patient Man in World" Who
Makes Lenses for Telescopes, Can
Show What It Is.

---
When Prof. Albert A. Nicholson, of
the University of Chicago, was making
his investigations of spectra for which
he was awarded the Nobel prize in ply
sizes in 1907. he found himself in need
of sixteen-inch parallel plates ground
to an accuracy of one millionth of an
inch. 1t was also necessary that he
have an interferometer enabling him
to measure the differences of lenses
varying one millionth of an inch or
less, that he might obtain the true
value of the standard meter. Appar-
entity DIR. Michelson's computations
lad led him to the impossible, and the
accuracy of their demands threatened
To pass the bounds of the practical.
Dr. Nicholson was in a quandary
when he heard of one Petitdidier, call
ed by faculty members in the univer-
sity the most patient man in tho
world. Petitdidier had been employed
by the University of Chicago to grind
lenses for the Yerkes Observatory
telescope. Acting upon the advice OF
his colleagues, Dr.. Nicholson sought
the lens grinder.
ON the door of an uninViting place at
5423 Lake avenue, Chicago, the eminent
physicist read the half-effaced legend,
Octave L. Petitdidier.' and walked III
He was greeted kindly by nervous
little man with big head, surmounted
by u heavy shock of coarse black hair.
In terse sentences DR., Nicholson made
known his needs. In sentences quite as
terse Petitdidier accepted the commits
sior and specified the time for the de-
livery of the lenses and plates. Or.
Nicholson was relieved, but dubious.
Petitdidiar set to work on the order
almost as soon as the interview closed
He worked three and half months.
ten hours a day. in a dark room Kept
at constant temperature. The eX-
IRENE care which it was necessary To
exercise with the plates and lenses al
most disrupted the health of Petltdi-
der but he turned out the order salts
faetorily and DR.. Nicholson was able
to continue his Investigations Dr.
Michelsons Investigations startled the
universe; but Petitdidier's fame spread
only to d select number of scientists.
Petitdidier is a dealer in optics, a
grinder of parallel plates for echelon
spectroscopes, a maker OF lenses Tor
telescopes. Patience IS the equivalent
of accuracy in his vocabulary ana MS
peculiar aptitude has drawn astfeno-
mers and physicists of international
repute to his dingy little shop in Lake
avenue He is an anomaly in the field
of science. He presents the spectacle OF
an amateur developing hobby INTO
an exact science in which he alone is
thoroughly proficient.
,I-ip &c the most
acting of professions known to modern
industry. The glass for the lenses
must be absolutely free from bubbles
and faws-a condition which is almost
impossible to attain in the huge pieces
needed for sixty-inch lenses Petitdialer
imports his glass from France anu
pays a price that would make the cut
glass merchants wish they could sell
their wares by the pounds at the same
price.
Even rough shaping lenses Is pro-
position of extreme difficulty. After the
crude shaping has been done with the
die designed for the lens, the grass
must be rotated thousands OF times ui-
der a chamois pad covered with pre-
para ton of rouge. This process canIot
he continued for more than two hours
a dey because of the expansion OF the
glass resulting from friction.
When the accuracy of the lens APP
proaches one hundred thousandth OF
an inch the real difficulties begin. Ihere
are no instruments fine enough %
measure the inaccuracies, and Petital-
der tests the surface by optical means
Every one is familiar with the fac'
that a glass prism shows different col
ors 1t is this refraction of ilSht tha'
betrays the inequalities to Petitdioler
Examining the entire surface OF the
lens time and again for minute Spots
of color that betray inaccuracies, ne
polishes here and there. slowly Work
Ing the lens into perfect shape:
Petitdidier calls his profession DIS
ease" and he has constantly to war;
enthusiastic professors against ABSORB
ton in the subject of the optics he
has had seven scientists under his ute
age. but before they progressed very
far in the work he cut short ms IN
structions. with, You had better cu'
If out now. 1t will get you just ike IL
got me. And once it gets you. you are
done for"
II was 30 years ago that the disease
got" Petitdidier. He was born in Vile