the 'weakeji Natural or Artificial EleSir icily. Lx 
conductor itfelf {hews either no electricity at all, or exceeding 
lmall ligns of it. 
4. It was mentioned above (IV.) that the conducting wire 
muft be left in contact with the metal plate for a certain time , 
the length of which, however, is not eafiiy determined, fince 
it depends upon variable circumftances. When the conductor 
itfelf (hews no figns of eledtricity, then it will be neceffary to 
leave the apparatus, as directed above, during eight, ten,. or 
more minutes. But if the conductor itfelf is capable of juft 
attracting a very fmall thread, then it will be fufficient to leave 
the apparatus in contadt as above mentioned, for a few feconds 
only, in order afterwards to obtain from it very confpicuous 
eledtrical appearances. 
r. Refpedting the condudting communication between the 
atmofpherical condudtor and the metal plate, care fhould be 
taken that it be made of the feweft joints poffible, or rather of 
one piece, fince the difficulty of tranlmitting very fmall quan- 
tities of eledtricity is confiderably increafed by every interrup- 
tion, and it may thereby be quite obftrudted, as is often the cafe 
when a chain is ufed for that purpofe.^ 
6. As for the eledtrophorus to be ufed, it mud: be farther re- 
marked, firft, that its being very thin, as mentioned above, is 
of great importance; it having been obferved, that the thinner 
the refinous ft rat um is, the greater quantity of electricity can 
be accumulated into the metal plate laid upon it; which is 
the cafe whether the eledtricity is brought to it from the atmo- 
fphere, as in the abovementioned inftance, or from any other 
electric power. The thicknefs of one-fiftieth of an inch, or 
that of a common coat ot varnifti, is very proper ; whereas 
if the refin w r as an inch thick or more, the experiments would 
anfwer very badly. 
7. Secondly, the furface of the refinous ltratum, as well as 
th/ under furface of the metal plate, muft be as plain and. as 
fmootli as pollible, in order that the two furfaces may coincide 
more perfedtly when laid one upon the other. It is well known 
how much this circumftance favours the effedt of the eledtro- 
niiorus; for this.reafon, in my publication on that inftrument, 
1 1 1 recommended 
