176 
WILLIAM SMITH : HIS MAPS AND MEMOIRS 
a brown red sandstone pebble the crystal of whicli brilliantly reflected 
the full light of the sun. Viewing it in the house, on a table before my 
window, with my spectacles on, and the addition of a small pocket lens, 
the glistening specks appeared too small for me to decide whether they 
consisted of quartz or mica ; but, as I had lately selected from the same 
gravel specimens of mica slate, and mica sandstones of all degrees of 
fineness, it occured to me that small specks of mica were always 
visible without the sun's full bright light. I found them so ; and, by 
collating the sandstone with the finest grained micaceous specimen^ 
both on one piece of paper shifted alternately into the bright and shady 
light of the sun, we have a clear and ready distinction, between the 
finest grains of mica and quartz, without the aid of glasses, and that 
even at a distance of 4 yards. 
" In my practical observations on the different kinds of land, I had 
long observed, by the glistening in foot-paths, how we may readily 
distinguish the finest sand in soil ; and, at Harrogate, I have often 
amused myself, on the nicely sanded footpaths about the Swan Hotels 
by fixing my eye upon any detached crystal (of mill-stone grit) which 
brilliantly reflected the light of the sun, and not without speculating on 
the application of such brilliant reflections to some useful purpose : but^ 
in geology, the brilliancy of those facets of quartz crystals in our 
coarsest sandstone seems to render doubtful the ' theory of sandstones 
being derivative rocks.' — 
William Smith, LL.D., Scarborough, May 10th, 1827." 
The next is entitled Coal-finding, and occurs on pages 645-647.* 
It is signed " William Smith, Scarborough. Sep. 29th, 1837/' and is 
as under : — 
" COAL FINDING." 
" In the mysterious business of coal-finding, we are warranted in 
making any reasonable experiments which may lead to a recovery of the 
range of the whole series of coal-measures, and in drawing inferences for 
our guidance in the choice of places of trial, from the most remote 
phenomena which seems to favour our purpose ; for the seemingly 
abrupt terminations of some of our coal-fields are certainly the most 
difficult problems in geology. Here, the practical man, with a vast field 
* The page number of this in the Contents " of the Volume is- 
wrongly given as 464. 
