TRANSACTIONS OF THE SECTIONS. 
57 
toning round in the gimbals, so as to bring its axis to coincide with the new axis 
tou endeavoured to give it, with a life-like precision, and always so as to make its 
oun direction of revolution be the same as that of the slightest turn you impart to 
it. Having thus demonstrated the necessary effect of combining one rotatory motion 
*/.h another, he then proceeded to demonstrate palpably that the earth's revolving 
cj.ju affected the gyroscope in precisely a similar way. Having, by the screw 
sijwtments, brought the gyroscope, in gimbals, to a very exact balance, it remained 
hid in any position when not revolving. But, rapid rotatory motion having been 
rmmitnicated to the gyroscope mass ns soon as the gimbal supports are placed on 
e.and, you see the entire apparatus, slowly at first, bat at length more rapidly, 
utn iiself round, nor ever settle until the axis, on which the gyroscope is revolving, 
* ru S cs ifcdf parallel to the terrestrial axis, in such n sense as to make the direction 
m die revolving gyroscope to be the same ns that of the whole earth. He next .showed 
■m. the determination with which it did this was sufficient to control the entire 
v.-ru i f the instrument, though that amounted to several poands; for, taking the 
Syrocopc, from the side of the ring of which a small steel wire projected, 
in a hook, the wire coincided with the prolongation of the axis of the gvro- 
u 01 coa rse, when not made to revolve, the hook, if placed in a little agate cup 
to P of a stand, would permit the instrument, bv its weight, to fall instantly, 
.„7 JD M the su PPort of the hand was taken from it. But, upon imparting to it 
ir- rutn * or y motion, it stood up even beyond the horizontal position, so as to 
of rotation nearly to the same inclination to the hori/.un as the oris of 
: w u^ e ihe whole acquired a slow rotatory motion round the point of the 
i S0 , steaJ -V waa its equilibrium while moving thus, that a string being 
liirivM er ,^ e book and both ends brought together in tile hand, the whole nug 
V T „ . y, t “ e cor< l off the stand and carried revolving steadily about the room. 
f-WridJ ,notion of the earth scnsiblv, he placed the gimbal gyroscope 
l‘U S W b - v a flnc silk fibre in a stand with the lower steel point of its sup- 
* -"imp.!"i ai .'. a 8 ute CU P ; along light pointer projecting from the ring can le 
w lti rt .u' V llcb H^^cd over a graduated card arch of a circle placed conce - 
index ' lhR Eyofcope ; upon imparting rapid rotatory motion to the gyroscop 
11 f tatiun 88 SG i en a * tbo eart -h moved to point out the relative motion of the p 
'nt oftj! Sf! y m tbe ; the law of the motion being also the same as 
“‘rtioD and |, pendulum experiment. Lastly, he set the ring gyro P 
q le ’’y lacing a small pointed piece of brass at the end of the axle on tl 
tii? floo r hnnw ent WL>nt ‘ m mediately through all the evolutions of a boy s j 
’ hUmni 'ug meanwhile loudly also. 
An A *comt 
r ‘J I’usion 
Bef, 
Of some Experiments on the Effect of Pressure on the Temperature 
fltf m °J different Substances. By W‘. Hopkins, M.A., 
L ‘ Cr "at obhlnr' 1 " 18 to give an account of these experiments, Mr. Hopkins stated 
‘"■-tanre, he u S r ..ff On0 , f ” Mr - Fairbairn for the promptitude with which, in ^ 
*ince afford To * lls assistance and cooperation, and the manner m g 
^^HhuSJ V ilid of h»s great practical knowledge and the ample means 
nlso ht efeTt en tr fford * for cun <lucting experiments of this‘ " atU J* ibe the 
J'^tus whioh 6 ^ "hhgations to Mr. Joule, lie then proceeded to d b 
’ r '' 3 ' been VISotl mid the causes of the successive fe' lurC9 ' ’J 
devised and constructed which was 
V ‘ Colt 7 luid bel f “ r u BU hstnnces sufficiently fusible to be experimented on. u ^ 
ln a ruetal t„i D . a$Ccrt *Mning the moment when the substance en > 
uT A small bccame but it had been overcome by the Mlnvmg V 
' ° f ab °nt a o P " 1l i 0u " f ‘he substance was pul into a Brass tube open at one .end. 
X t,1(i of * ,X an iach ^ diameter, and was then molted. » *£■ 
firal V ' l " c1 ' the Lw Ucedlc Wiva inserted in it to the depth of a,,out b ‘ hccom in°- 
c25[ fixe <l in it b ?, anC0 Wsis left to cool and solidify, the needle pLmbe 
U^t'hcatinu ‘ •„ 10 tu be was then screwed on to the extremity ol. su b_ 
^l^rinfented 1 tt Vertk ' ul c >' linder filled with oil, the tube con JjTLisg the 
d on, and the magnetized needle being also vertical. 
