Wood County reporter. [volume] (Grand Rapids [i.e. Wisconsin Rapids], Wis.) 1857-1923, 1891-01-08

of astronomy there. This place he held
until 1886, when he resigned to accept the
chair of astronomy and physics at Colby
university, Waterville, Ne, which he
still retains.
While at Alfred he superintended the
building Of the observatory there. and ar
ranged for its equipment; while at Har-
ward his special work consisted in observ-
ing and mapping all the stars down to the
ninth magnitude in narrow belt of FIVE
degrees, located little north of our zenith.
This work has been done under the aus
plces Of the German Astronomical soci-
ETY., OF which he Is a member Four or
five volumes of these observations have al
ready been issued, and others are in prep
aratlon.
His special reputation, however, has
been made IN mlcrometry. One of the
first difficulties that he met with in his
work was the finding of micrometer spider
webs that were suitable for his purpose.
he then began series of experiments in
order to find a practical method of etching
lines on glass. After many fruitless eff
forts, the desired result was obtained by
making a film on the glass. cutting the
lines to be etched through this film by
means of still point, and exposing the
plate thus prepared to the fumes of hydro
fuoric acid confined in a close vessel at
the particular point of time when the
fumes contained the proper degrees of
moisture to give them the maximum effici-
ency.
The success was so complete that he Sc
cured an order from the United States gov.
eminent for the plates which were used by
the expeditions that were sent out from
thus country to observe the two transits of
Venus. For upward of sixteen years he
has closely studied this subject, and his
knowledge of it has made him the uniyers
ally acknowledged authority in all that per-
talns to mecrometrical work. ,
Professor Rogers has also made a speci
| atty OF the construction of comparators fo1
| the determination of differences in
| lengths, thus establishing useful working
standards of measurements for practical
mechanical work. This research resulted
in the Rogt rs-Bond universal comparator
built by the Pratt & Whitney company, OF
Hartford, who were thus enabled to estab
llsh their system Of standard gauges. In
1880, he was sent abroad at the expense
of the American Academy of Arts ana
Sciences to obtain authorized copies Of
the English and French standards OF
length. These were used as the basis Of
comparison for the bars that he construct
ed, and which now serve as standards OF
of length for Harvard, Yale, Columbea,
, Princeton, the United States signal ser.
vice bureau, the Lick observatory and 9th.
er institutions.
Besides other Investigations of practical
value Professor Rogers deserves credit fol
his micrometer rulings, made both OF
glass and metal, which are especially ap
preciated by mlcroscopsists for the accu
racy ..as regards division and also the
character and beauty of the lines.
The degree of A. III. was conferred upo1
him by Yale in 1876, and he received that
of Phi. D. from Alfred in 1886. He was
vlce-president Of the ,American Association
for the Advancement of Science in 1888
presiding over the section on mathematics
and astronomy, and in 1886 was president
OF the American Society Of Microscopists
He was elected to the National Academy
of Science in 1885,