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A new pendulum suspension
July, 1880.]
,>))el/ier-- I)ei.f
,I.,,,
o'.
A - = 2 . . . . . :. . . .
i
,'.,,..TJe.si,.<
17
i
This tbrmula, with supposition of n ~ ~ bceomes exact, and will be A " 7F3~53R2 6"1803 When g = 360 ° A =_4~R 3
2; or A =
i re'C 2. 3 This last formula and formula (3) can easily be memorized, and although they are not in use in ordinary problems of mechanics, it would be not superfluous to introduce them ill some manual of .engineering.
A NEW PENDULUM
SUSPENSION.
By Lov~s H. SPELLIER, The time-keeping qualities of a clock are almost entirely dependent upon the correctness of the pendulum, and ever since its introduction as a medium to divide time into equal intervals, it has received tho very greatest attention accordingly. As it is the object of the compensation of the peudulum to kee l) its centre of gravity regardless of change of temperature, at an equal distance from its centre of oscillation, so its suspension should allow only its re-occurrlng oscillations to follow the track of a straight line and to move in a straight plane only. The chief if not tile only condition to arrive at this result is to give the suspending spring an even tension. Uuless this condition is complied with the oscillating pendulum will be accoml)auied by the well known wabbling side motions which so greatly intertbre with its correctness. Pendulums have been suspeuded on one as well a~ on two springs, the latter of which is almost entirely abandoned. None of the suspensions so far had. a contri'~ance which would automatically adjust the tension of tlie suspendingspring, and so with nr.tthemttieal cq'tainty avoid the wabbling motion alluded to. The author claims to have succeeded in constructing sttch a suspension. It solves tile ])roblem perfectly.
Spellier--Pendulum Suspension.
48
[ J o n r . F r a n k . Jnst~
A is a tube screwed on to the supporting base G. B is a round piece covering and fitting into the tube A. Through the centre of goes a screw-threaded spindle C, which bears on its lower end, between a tbrk-like cut, a pulley D. F is the pin on which the pulley turns. and extends through opposite cuts ifi the tube, to prevent C a n d D' from turning when B is turnecl to lower or raise the pulley D.
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!
i
I!
.i!c i I\,
.t
/2
--
/
t ?I
[il ~
i i K
N
~i!i
Over the pulley the suspending spring e lies, and its two ends are fastened between the two bars K K . The two plates H H are screwed against the under part of G, and just far enough apart to allow the ends of the spring to extend laterally through the slit they form. I f now the pendulum hangs on the L its weight will bear equally on either side of the spring by means of' the pulley, and adjust its tension automatically. How perfectly that suspension adiusts the tension can be seen if we bring the bars ASKinto the position shown by the dotted lines. Eveu this abnormal position will not interfere with the pendulum in performing its oscillations in a true plane. While with other suspensions it would be impossible to avoid the wabbling motions if K a n d H would wtry the least ii'om being parallel.
,>))el/ier-- I)ei.f
,I.,,,
o'.
A - = 2 . . . . . :. . . .
i
,'.,,..TJe.si,.<
17
i
This tbrmula, with supposition of n ~ ~ bceomes exact, and will be A " 7F3~53R2 6"1803 When g = 360 ° A =_4~R 3
2; or A =
i re'C 2. 3 This last formula and formula (3) can easily be memorized, and although they are not in use in ordinary problems of mechanics, it would be not superfluous to introduce them ill some manual of .engineering.
A NEW PENDULUM
SUSPENSION.
By Lov~s H. SPELLIER, The time-keeping qualities of a clock are almost entirely dependent upon the correctness of the pendulum, and ever since its introduction as a medium to divide time into equal intervals, it has received tho very greatest attention accordingly. As it is the object of the compensation of the peudulum to kee l) its centre of gravity regardless of change of temperature, at an equal distance from its centre of oscillation, so its suspension should allow only its re-occurrlng oscillations to follow the track of a straight line and to move in a straight plane only. The chief if not tile only condition to arrive at this result is to give the suspending spring an even tension. Uuless this condition is complied with the oscillating pendulum will be accoml)auied by the well known wabbling side motions which so greatly intertbre with its correctness. Pendulums have been suspeuded on one as well a~ on two springs, the latter of which is almost entirely abandoned. None of the suspensions so far had. a contri'~ance which would automatically adjust the tension of tlie suspendingspring, and so with nr.tthemttieal cq'tainty avoid the wabbling motion alluded to. The author claims to have succeeded in constructing sttch a suspension. It solves tile ])roblem perfectly.
Spellier--Pendulum Suspension.
48
[ J o n r . F r a n k . Jnst~
A is a tube screwed on to the supporting base G. B is a round piece covering and fitting into the tube A. Through the centre of goes a screw-threaded spindle C, which bears on its lower end, between a tbrk-like cut, a pulley D. F is the pin on which the pulley turns. and extends through opposite cuts ifi the tube, to prevent C a n d D' from turning when B is turnecl to lower or raise the pulley D.
[
!
i
I!
.i!c i I\,
.t
/2
--
/
t ?I
[il ~
i i K
N
~i!i
Over the pulley the suspending spring e lies, and its two ends are fastened between the two bars K K . The two plates H H are screwed against the under part of G, and just far enough apart to allow the ends of the spring to extend laterally through the slit they form. I f now the pendulum hangs on the L its weight will bear equally on either side of the spring by means of' the pulley, and adjust its tension automatically. How perfectly that suspension adiusts the tension can be seen if we bring the bars ASKinto the position shown by the dotted lines. Eveu this abnormal position will not interfere with the pendulum in performing its oscillations in a true plane. While with other suspensions it would be impossible to avoid the wabbling motions if K a n d H would wtry the least ii'om being parallel.