Wilmington daily commercial., 1873-12-22
Del. Institute Of prechnnic Arrs.

IEoruRR BY THEo. aRIBI on TIE PENDULUM.
According to announcement in our Fridays
issue, Mr.. Theo Crib delivered lecture IN u
room of the above association on the Pendulum,
ON Saturday evening. After brief introduction,
Mr.. Crib commenced by giving general deb-
nition of the pendulum. He said that we dis.
tinpuished between the simple or theoretical.
and the compound or material, pendulnm-that
the former had no existance except in the brains
of philosophers, but was simply USED ior
the PURPOSE Of explaining the phenomenon oi
the movement and investigating the laws which
govern the material or real pendulum and thus
10 establish a reasonable theory OF 1t. lie then
went On to analyze the oscillations OF pendu-
INN mathematlc llv, and proved the reasoning
bv governmental illustrations with three balls
which he bad suspended by hue strings OF une-
aual lengths. go as to show the relations when
exist between the number Of OSCILLATIONS OF PEN
dulums and their lengths.
crrians feature was pointed ont in the fact.
that no matter what the weight OF pendulum
NAV be il its length is not alteted. II VIII MAKE
| tho came number of vibrations IN gwen time
| aud he showed by an Illustration that TINS was
owing 10 a charact teTstlcof the force OF gravita
| tion. by which the motions of the pendulum arc
| gov yerned, and by which all bodies whether
heavy or light, il dropped from the same height
/ would fall to the ground IN e1aely the same
i time. =,
He divided his lecture into two parts first the
| theoretical investigation of the pendulum, ana
the practical application of it and its history and
i uses He showed that by the pendulum we can
prove the variablenes of the force of graviatton
/ and thence tho spheroidal shape. and the dinr-
i nal rotation OF the earth, but that by far tie
i most important use to which the pendulum had
i been subservent in its application TO
i the measurement OF time.
| The lecturer here related the history OF the
i measurement of time from tho earliest times
down to the present moment, aud how the Narl'
i ous practical methods for dividing the time rue
i ceeded each other. He showed that tue stand
i ard for the measurement of time was given at
| the creation when God said Let there be lights
| in the armament OF the heaven to divide the
| day from the nigh I; and let them be four signs
| and for seasons and for days anu yesrs, Gsn l
| Ia and that this standard was the same to-day
| The first means for dividing day into smaller
| portions OF time consisted in UPRIGHT poles,
| whose shadow indicated the commencement and
decline of the day These were sundals. Then
came the clep-ydrae, the hour glasses, aud II
was not until tho latter part of l4th cettury thai
| any mechanical coutrivances were ured Tor the
| purposes of measuring time. The fret was the
clock built by a German by the name of Henry
DeVic, for King Charles v. in 1879
| The pendulem was discovered oy Gdllleo, IN
the 17tli century. and the first application OF II
| TO the measurement OF time made in 1857
by Christian Hughens, celebrated Dani7l
mathematician.
| During the course OF the lecture many curl
| ous aud interesting features connected with the
| measurement OF time were pointed out.
The room was foil and the audianct
listened with marked attention for an hour snt
| a half At the close OF the lecture Rev. MIR. Is
erael proposed a vote of thanks to Mr. Gribi
which was unanimously rendered. The subiec
| proposed for the next lecture was The Air VI
| breathe" and DIR. Grimshaw was requested t
lecture ON that subject at a future occasion.