f 
Professor Leslie on Electrical Theories . 
closet. About a twelvemonth afterwards, he revised it, made 
some slight alterations, and annexed a few explanatory notes ; 
and, in this state he has suffered it to remain ever since, design- 
ing always to resume with vigour and effect the decisive experi- 
ments planned in it. On perusing it again, after such a long inter- 
val of time, far exceeding the limits of the Horatian precept, the 
author, though not quite satisfied with some of the mathematical 
explications, is convinced of the accuracy of the facts, and train 
of reasoning, and of the soundness and importance of the gene- 
ral conclusions. These leading views and experiments have 
been successfully introduced by him into the Lectures on Elec- 
tricity which he has given since he began to teach the class of 
Natural Philosophy. The memoir is now printed from the ori- 
ginal manuscript, with merely slight verbal corrections ; but 
some illustrative annotations are subjoined in Italics, exhibiting, 
under a different form, similar experiments and deductions. 
The author intends, however, without any farther delay, to re- 
sume those interesting electrical inquiries, and hopes to be able 
very soon to lay the results of his extended researches before 
the public.]] 
JCjlectrjcity may be justly regarded as the most striking and 
attractive part of Natural Philosophy. Deriving its origin from 
remote antiquity, it is yet altogether of modern growth, having 
shot up with amazing rapidity during the course of the last half 
century. It wants, therefore, the ripeness and solidity which dis- 
tinguish all the branches of mechanical science. In the forma- 
tion of electrical theory, inferences are drawn from the most fan- 
ciful analogies; and the imagination and the senses consulted ra- 
ther than the understanding. Already we are in possession of 
numerous and important facts ; and it is time to survey, with 
a curious and sceptical eye, our real progress, and to ascertain 
whether the received doctrines of Electricity deserve the honour- 
able appellation of science , or ought to be regarded as the super- 
ficial production of fancy. 
It may, perhaps, he deemed presumption in me to treat the re- 
ceived hypotheses with such liberty. But, in matters of this kind, 
free discussion should be indulged, and opposition even encou- 
raged ; and a dispassionate inquiry promises the more success, 
since the enlightened and profound philosophers have in general 
