Descriptum and Use of a very sensible Electrometer. 
columns which Behrens had placed without the glass, which 
defences the gold-leaf from the agitations of the air, are placed 
within the glass, so that their position is not only better pre- 
served, but they are defended so completely from moisture, dust, 
&c. that they retain the same electrical intensity. 
This electrometer is used in the following manner : The cap 
of metal is put in communication with the ground by means of 
a metallic wire, and by touching the brass-ball, any accidentai 
electricity is discharged, which may belong to this part of the 
apparatus. If one has a dry skin, the touch of the hnger k 
not sufficient. As the gold-leaf is suspended between the 
columns, at the level of the rings of metal which terminate 
them, the one positively, and the other negatively, the gold-leaf 
is attracted equally on both sides, and remains quietly in the 
middle in its ordinary state ; but if, by means oi* the metallic 
wire, we communicate to it the weakest degree of electricity, 
the lower extremity of the gold-leaf is attracted by the ring, 
which possesses an electricity opposite to that which is commu- 
nicated. Having come in contact with this ring, it is successive- 
ly repelled and attracted by the opposite ring. This oscillatory 
motion continues till the gold-leaf attaches itself to one of the 
eolumns, from which it may be easily detached by touching the 
brass-wire, so as to dissipate its electricity, and by shaking the 
instrument. In order to determine the nature of the electricity, 
the upper poles of the two columns which project above the 
brass-cap have the signs -f- and — upon them, and the electri- 
city required is that which is indicated by the sign of the co- 
lumn towards which the gold-leaf first moves, or which it first 
touches, when the electricity is stronger. 
By this electrometer, strong and weak degrees of electricity 
may be equally well examined. In the first case, the electrified 
body is made to approach slowly and at a distance the ball of 
the electrometer, till the gold-leaf is put in motion towards one 
of the columns. If, for example, we bring an excited stick of 
sealing-wax to the distance of about three feet from the . ball, we 
shall observe a motion of the gold-leaf towards the column mark- 
ed — . If we bring it to a less distance, it will strike the column, 
from which it may be easily detached, by bringing the wax still 
nearer. In the second case, the electrified body must be moved 
