On the Construction of De Lwuc’s Columns. 137 
Last winter, wishing to. replenish the tubes of a. pair of electric 
columns which had become effete, I contrived to avoid the risk of 
expending the labor and attention requisite to finish a series, while 
uncertain as to its eventual efficiency. I contrived likewise, by a 
very simple expedient, to facilitate the process of piling the disks. 
- The first mentioned desideratum was obtainéd by means of a sin- 
gle leaf of gold, suspended in a glass vessel, (represented by the 
subjoined figure,) between two knobs at the end severally of two 
brass rods B B, proceeding through opposite sides of the vessel to- 
wards each other, so as to be capable, if requisite, of meeting in the 
center. By means of screws, the knobs on these rods, were suscep- 
tible of being adjusted to any distance from the gold leaf, suspended 
between them. Externally the rods are so made and placed, as to 
be easily connected with wires. In the gold leaf thus situated, vibra- 
tions may be produced by a series of disks, comprising not more 
than one twentieth of the number necessary, to cause such a pendu- 
lumn as commonly pertains to the electric column, to oscillate. In 
the case in point I found that the disks produced by one sheet of 
paper, were sufficient to make the leaf vibrate actively between the 
knobs. ‘The mode in which this effect was produced, ‘be un- 
. XXV.—No. 1. 
