82 Sir W. Snow Harris’s Researches in Statical Electricity. 
2. I omit for the present all especial account of the several 
processes and electrical instruments of research employed in these 
inquiries ; they are for the most part such as I have described in 
former papers in the Royal Society’s Transactions, viz. the Hydro- 
static Electrometer, the Scale-beam Electrometer, Unit-jar, Bifilar 
or Torsion Balance, Quantity-jar, &c.* I will merely observe, that 
Ihave, since my first announcement of these instruments, greatly 
improved them, and carried processes of quantitative measurement 
to a remarkable degree of precision, so that given and measured 
quantities of electricity may be deposited with perfect certainty 
on insulated conducting surfaces, the intensity or reactive force 
accurately deduced under a great variety of circumstances, of 
form, extent of surface, variation of distance, or any other ele- 
ment essential tothe inquiry. I have further given most especial 
attention to the perfection of the several insulations upon which 
the accuracy of important deductions mainly depends. Wherever 
it is admissible, the conducting bodies are insulated by suspen- 
sion filaments of strong silk-gut, carefully varnished with a solu- 
tion of shell-lac or naphtha, and sustaimed by varnished glass 
supports, so that an extremely small surface is exposed in such 
kind of insulation. The glass rods and other solid insulators 
employed were also carefully varnished, and as slender as the 
nature of the experiment would admit, and were made perfectly 
dry when employed, by the dry heat of a curved iron heated to 
redness. By these means, and with attention to the air of the 
room, I have been enabled to retain the quantity-jar and needle 
of the balance in a charged state for two and sometimes three 
days together, and that, too, without much deterioration of 
charge. Suspended insulated conductors of some considerable 
extent have been observed to perfectly retain the quantity of 
electricity communicated to them, and far exceeding the time 
requisite for the experiment under examination ; so that all cal- 
culation of loss of charge by atmospheric influence, and which 
is commonly a very precarious matter, became altogether eli- 
minated in the inquiry. 
3. Preliminary views.—If an insulated neutral conductor, N, 
Plate I. fig. 1, be immediately opposed to an insulated charged 
conductor P, then, as is well known, a peculiar and very extra- 
ordinary species of action ensues,—an action apparently of a 
sympathetic kind, and which at first seems to be an action ex- 
erted between the two bodies at a distance. The result of this 
action, whatever it be, is to change the actually existing electrical 
condition of the two bodies; e. g. the neutral body N, without 
any direct communication of electricity, exhibits a state of elec- 
trical excitation and becomes attractive of surrounding matter, 
* Transactions of the Royal Society for 1834, 1836, 1839, 
