508 OBSERVATIONS ON THE FORMATION 
"KIA. —Observations on the Formation of the 
various Lead-Spars. 
By Mr James Biiaid, Surgeon, Leadhills; 
Contained in a Letter to Charles Anderson, M. D, 
M.W.S. &c. Leith. 
{Read 5th April 18^3.) 
Dear Sir, 
It is more than four years since I first hinted to you my 
opinion regarding the formation of the different lead-spars 
found in the mines here; and now, after various oppor- 
tunities of repeating my observations on the same subject 
(which confirm the opinion then stated), I most readily 
comply with your late request, of communicating to you 
my ideas on the subject, in a more extended and perfect 
form, than then given. 
I had not resided long at Leadhills, before the appear- 
ances presented by the various spars of lead found in the 
mines, — the nature of the situations in which they most 
generally occur,.^ — and the peculiar circumstances which en- 
