50 Account of an Electrical Increaser for the unerring 
communication of too great a number of deposits having no cther 
tendency than that of marring our operations. The size of my 
present one, as I have already said, is about six inches in diame- 
ter ; and even with ¢his, the pillars must neither be over-heated 
nor rubbed: while, to fit the instrument immediately for a se- 
cond experiment, it will be necessary to touch every plate (all 
the plates are unvarnished brass] for at least a dozen seconds, 
with a similar metallic substance. 
“TI must not close this letter without pointing out to your 
Lordship a striking circumstance which for a long time escaped 
my observation. If the electricity communicated to the source 
be tolerably zzéense, it will be almost if not wholly imperceptible: 
it will overcome the resistance opposed by the plate of air, strike 
the carrier, and pass into the earth. A small piece of well ex- 
cited sealing-wax would, in most instances, overcome a plate of 
air of one inch diameter and perhaps one-sixth of an inch in 
thickness. For the most delicate experiments, | should consider 
the one-fortieth of an inch about the distance best suited. This 
will discover the electricity of a piece of glass when moderately 
heated,—for heat, beyond denial, as this instrument will prove, 
excites to action the electric fluid in bodies of almost every de- 
scription, Cold, as every electrician knows, produces an oppo- 
site effect: Water frozen to 13° below 0 upon Fahrenheit, be- 
comes an electric. 
“© May not these well-ascertained facts be more closely ap- 
plied than usual to the doctrine of thunder ? and should we not 
therefore look to the torrid and frigid zones for the grand solu- 
tion of the phenomenon ?” 
Explanation of the Plate. 
» COLOURS. 
Brass unvarnished—represented by the yellow. 
Glass varnished ove os «. black. 
Mahogany .. — wie -. brown. 
Parts of the Instrument. 
A, The source, a brass plate (one inch and three quarters dia- 
meter) to which the body for examination is applied. 
B. The revolving carrier, a brass plate (one inch and three*quar- 
ters diameter) which drawing the electric fluid from the 
scurce, without impoverishing that scurce, deposits the 
fluid so drawn upon the reservoir. 
cC. The combined reservoir, likewise brass, the smaller plate ¢ 
being one itch and three quarters diameter, the larger C 
six inches. The accumulated fluid must be ultimately 
concentrated upon the’smaller one, by a process similar to 
that observed in using the ordinary combined condensers. 
D, A brass 
