( * 4 ° ) 
VL An ExtraCt of a Letter from James 
Logan, Efq ; to Sir Hans Sloane, Bart. 
R. S. Tr. concerning the crooked and 
angular Appearance of the Streaks, 
or Darts of Light’ning in Thunder- 
Storms. 
Philadelphia, Sept. 20 , 1735 *. 
I Shall crave thy Indulgence further to add, that 
looking into the Second Volume of that inge- 
nious Gentleman Stephen Hales’s Staticks, of 
which I have lately happened to have a curfory 
View, I oblerved him to mention that Phenomenon 
of the Streaks or Darts of Light’ning in Thunder- 
Storms appearing crooked and angular (Ido not re- 
member his Words) as a thing not yet accounted 
for ; and therefore he gueffed at a Solution of it*. 
The Clouds are generally diflindt Collections of 
Vapours like Fleeces* and therefore the Rays of 
Light thro’ them mud pafs thro’ very different Den- 
fities, and accordingly fuffer very great Refractions ; 
From thence therefore, undoubtedly, that Appear- 
ance muff arife. For it is molt highly abfurd to ima- 
gine, that Fire darted withluch a Rapidity, can from 
any aflignable Caufe deviate in Fadt from a Right 
Line, in the Manner it appears to us. And this, if 
duely confidered, may probably be found a plenary 
Solution. 
Z See Steph. Hales’; Statical EJfays Vol. ad, p. 191. 
Obfer > 
