216 Answer to Geological Queries of ** A Constant Reader.” 
the gentleman has ascertained by direct experiment that such @ 
redundancy of salubrious air exists in the southern regions, I am 
at a loss to know. I hope he will have the goodness to point 
out the plan by which he ascertained such an important phe+ 
nomenon; which will confer a favour on, 
Sir, yours, &e. 
Dorset Street, Salisbury Square, J. Tatum. 
Sept. 9, 1617. 
P. S.—Any hints from your correspondent Mr. J. Acton will 
confer a favour, as perhaps I shall pursue the sybject next spring, 
XXXVI. Answer to Geological Queries of ‘* A Constant 
Reader.” By Mr. WestcGarts ForTER. 
To Mr. Tilloch, 
SIR, — I HAVE observed in your Number for July last, some 
geological queries, by your correspondent, with the signature of 
** A Constant Reader,”’ requesting an early answer thereto. 
I therefore take the opportunity of informing him, with re- 
spect to his 2d question, (“¢ whether or not the great whin sill, 
or stratum of basalt, shown in p. 152 of my Treatise ona Sec- 
tion of the Strata, &c. has not such a continuous edge on the 
surface, as clearly indicates it to form, like each of the other 
rincipal strata, a vast extended plane having curved parts within 
‘e earth, &c.”’) That wherever I have made observations, or 
ced the great whin-sill, it is as conformable as any other stra= 
be although very variable in thickness, having its under lieing 
me lieing strata. And it may be traced upwards of fifteen 
mil commencing a little below the smelting-house at Tyne- 
heatvhere it is thrown up to the SW. about sixteen fathoms, 
Y “influence of a great dyke or vein, commonly called the 
aCk-me, or Great Sulphur Vein. As we proceed, a little 
above ts smelting-house, it disappears, about the distance of 
two mile. haying its over lieing stratum upon it; viz. Tyne- 
b ottom lirnstone, &c. until we arrive at the river Tees; where 
it again Mies its appearance, the Tees running upon it almost 
all the way . the high waterfall at Caldron Snout, where it as- 
sumes locally ¢/,¢ appearance of detached and over lieing masses 
of basalt; wh.h, as Mr. Winch observes, may very probably 
resemble those ¢ the King’s Park Edinburgh. It may be also 
necessary to stat, there is a level drove in the limestone, under 
the great-whin-sil, not far from Caldron Snout, and near the 
conflux of the tive Tees, and Maize-Beck ; and this Beck, or 
rivulet, which divims the counties of Westmoreland and York- 
shire, near Birdale, nns all the way for the distance of a mile or 
: more, 
