bert had imbibed the schoolmen's ideas as to the
relations of matter and form. He had discovered and noted that in the
magnetic attractions there was always a verticity, and that in the
electrical attractions the rubbed electrical body had no verticity. To
account for these differences he drew the inference that since (as he had
satisfied himself) the magnetic actions were due to _form_, that is to say
to something immaterial--to an "imponderable" as in the subsequent age it
was called--the electrical actions must necessarily be due to _matter_. He
therefore put forward his idea that a substance to be an electric must
necessarily consist of a concreted humour which is partially resolved into
an effluvium by attrition. His discoveries that electric actions would not
pass through flame, whilst magnetic actions would, and that electric
actions could be screened off by interposing the thinnest layer of fabric
such as sarcenet, whilst magnetic actions would penetrate thick slabs of
every material except iron only, doubtless confirmed him in attributing the
electric forces to the presence of these effluvia. See also p. 65. There
arose a fashion, which lasted over a century, for ascribing to "humours,"
or "fluids," or "effluvia," physical effects which could not otherwise be
accounted for. Boyle's tracts of the years 1673 and 1674 on "effluviums,"
their "determinate nature," their "strange subtilty," and their "great
efficacy," are examples.

[135] PAGE 53, LINE 9. Page 53, line 11. _Magnes vero...._--This passage
from line 9 to line 24 states very clearly the differences to be observed
between the magnetical and the electrical attractions.

[136] PAGE 53, LINE 36. Page 53, line 41. _succino calefacto._--Ed. 1633
reads _succinum_ in error.

[137] PAGE 54, LINE 9. Page 54, line 11. _Plutarchus ... in quaestionibus
Platonicis._--The following Latin version of the paragraph in _Quaestio
sexta_ is taken from the bilingual edition publisht at Venice in 1552, p.
17 _verso_, liber vii., cap. 7 (or, _Quaestio Septima_ in Ed. Didot, p.
1230).

"Electrum uero quae apposita sunt, nequaquam trahit, quem admodum nec lapis
ille, qui sideritis nuncupatur, nec quicqu[=a] a seipso ad ea quae in
propinquo sunt, extrinsecus assilit. Verum lapis magnes effluxiones quasdam
tum graves, tum etiam spiritales emittit, quibus aer continuatus & iunctus
repellitur. Is deinceps alium sibi proximum impellit, qui in orbem circum
actus, atque ad inanem lo