Weekly national intelligencer., 1851-08-09
ASTRONOMICAL MACHINERY.

Messrs. CALLS &c SEAroN: In the reduction of de-
vice to practice every one conversant with such matters
knows that approximate perfection is only obtained by
experiments and repeated trials and reecions WATT
was twelve years in peecng the steam engine, and in the
mean tme BoLToN, the moneyed patron OF the improve
msn had advanced several fortunes which consumed
in experiments. The first chronograph clock made for the
National Observatory not finished before it disco
vered that improvements could be made in it. and second
Immediately commenced, in which greater
nence Of manpulaons especially studied That second
Withdrawn to receive like improvements This second clock
much in model like the 6rst but the pendulum, instead Of
being made Of glass; is made entirely Of Steel the weight
lower part Of it consisting Of five thin tubes Of Steel each
about inch in diameter filed to the depth Of six
inches with mercury This model of steel tubes
mended to me by Mr.. Saxon. Such pendulum is
TALLY better than glass but Is not liable to acci
dent and the wokmen, in cleaning and repairing it. handle
il with the more confidence.
have also erected at the Observatory improved model
Of the registering cylinder which, being covered with sheet
of paper two feet square, receives the work Of the Observa
tory in fine punctued markings exactly like needle pune
These impressed in spiral lne generated by the
rotation Of the cylinder per minute and progressive
motion Of the puncurng sle BY these motions line Of
dots representing seconds is made about five hundred feet in
length and corresponding TO four hours Of time. the dots be-
ing half inch apart The observation marks also
punctured dots entering the line and subdvding the
second aconaly. When the sheet Of paper is cut open
and developed presents all Of the work Of four hours in
tabular FORM which the times hours minutes seconds
and minute fractions Of second at egbe by the
tesecons Of the lines Of dots which straight in two dec
TONS This developed sheet permanent record and forms
convenient leaf Of folio volume.
Without referring the mechanical imperections Of cy
nde as first introduced into telesraphc operations will
state briefly the points Of Improvement which have adopted
in this cylinder The cylinder roates short plain pvots
without progressive motion, is impeled BY weight, and
sused by FrauenhoGsr centrifugal clock It susceptible
Of being impeled by magnetism The registering head,
bearing the magnet and the pen, has progressive motion
rails parallel the axis Of the cylinder This progressive
motion produced by small clock under the table Of the
machine, the regenghead being attached to the cord o
the clock, which passes Pulleys for that purpose By
this MEANS and BY joint in the regstengpen, BY which
is prevented from dragging the paper the cylinder is left
free to without embarrassment and without any vary
ing friction, and thus takes uniform velocity. The cylin-
der which is Of metal feet long and eight inches in d.
ameer, is covered with velvet which is the sheet d
paper The velvet pile presenting little resistance tc
the needle point Of the se permits the perfect pYncts
Of the suPerimposed paper in conadsncon to the mere
denfaons Of paper in the Morse et Of the ordinary
telegraph These punctures have the advantages Of being
definite, egibe, and permanent. Some Of the above i'm.
provements have been currently announced in your pspe
before, but have thought not improper repeat them
thus in conne1on with their actual introduction into the Na
tional Observatory. JOHN LOCKE.
WAsHIseros, Aueusr 8, 1851.