386 PELTIER ON THE CAUSES OF THE 
20. In order to come as near as possible to the terrestrial con- 
ditions, and to cause the electrometer to be affected by the in- 
duction of the greatly inclined electric rays, I take a copper — 
globe, 40 centimeters in diameter, fig. 2. a a, having an opening 
b of 16 centimeters. This globe rests on cakes of resin cc, in 
order to keep it insulated. 
A small cord d is attached to a bobbin e, which turns with — 
difficulty, and which is fixed on an immoveable rule /; the small 
cord traverses a pulley g, suspended from the ceiling ; in the eye 
at its extremity passes a hook hf, sealed in a stick of gum-lac 7; 
at the bottom of this stick of gum-lac is fastened a screw J, from 
which is suspended a very small electroscope k& by its rod g. To 
the plate / is attached a metallic wire m, which always touches 
the bottom of the globe by its inferior extremity, furnished with 
a ball of copper, n. 
21. By means of the revolving bobbin e and of the cord d, — 
which is rolled upon it, the electroscope k, which is insulated at 
its upper part by the stick of wax i, may be raised or lowered. 
By means of a metallic wire 0 which is held by along and slender 
handle of gum-lac p, the rod of the electroscope g may be made 
to communicate with the globe, and thus occasion perfect equi- — 
librium of electric tension, without either the experimentalist or 
the terrestrial globe playing any part in it. The electroscope is — 
lowered until the stem from gq to/ is in the interior, it is held in © 
contact with the globe by means of the conductor 0, then a 
powerful resinous electricity is communicated to the globe. Like — 
the rod, the gold leaves z z and the armatures ss are in equili- — 
brium of reaction, the gold leaves do not diverge. The commu- — 
nicating wire is removed by its insulating handle p, and the rod 
of the instrument is then insulated. 
22. By means of the bobbin e the electroscope is raised one 
or two centimeters ; the leaves immediately diverge, and then 
indicate a vitreous tension, if the globe is resinous. If the elec- 
troscope is again lowered, the leaves return to zero. When the — 
electroscope has been raised and when the leaves diverge vitre- _ 
ously, if the rod g is put in communication with the globe, a 
new equilibrium takes place, the leaves again fall to zero; but 
if, setting out from this point, we lower it to that which it oc- 
cupied before, the leaves then diverge and are resinous. Thus, 
when a passage has been given to the free electricity of the rod 
q, it is the vitreous electricity of the leaves which has flowed off, 
