On the Construction of De Luc'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 obtained 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, may be un- 



VoL. XXV.— No. 1. 18 



