104 «= J. M. Safford on Petroleum in Southern Kentucky. 
disc H, the type which — the decimal of the second may 
either come in line wit which gives the whole seconds, or 
half a space above it, hoe 25°18 or 258; the first would be 
read twenty-five and eighteen hundredths, the second twenty- 
five and nineteen hundredths. 
_ It is not intended to secure precise coincidence of error be- 
tween the clock and chronograph—merely coincidence of rate. 
This is obtained by controlling the pendulum of the spring-gov- 
ernor from the clock. The type-wheels can be set so as to indi- 
cate the nearest whole second; and then the exact difference be- 
tween the clock error and the chron ograph error can easily be 
found by making the clock record itself Seeanieleally at the be- 
ginning of a minute. 
The operation of the instrument is then as follows. When the 
observer oe his key, the magnet Z acts upon the armature, 
and withdraws the pin d from its engagement with 4, causing it 
to plunge Pao one of the hundred holes in the dise H. The con- 
tact of d with H in its turn, by a magnet not shown in the cut, 
brings sai the hammer upon the paper 0 0 and forces it against 
the type, a piece of impression paper being interposed. - 
When the observer takes his finger from the key, d returns to 
its original position and will engage with dat its next revolu- : 
tion. The hammer also rises, and in rising caietes the paper 
along one space in readiness for the next impre 
As yet the printing chronograph exists wily ke as an idea, but 
it is hoped that the idea will soon be realized, and the machine 
put in operation at the Shattuck Observatory. The result of 
the experiment will form the subject of a future communication. 
Dartmouth College, April, 1866. 
ecient 
Art. XVIII.—Note on the geological position of Petroleum Reser- 
ri in Southern Kentucky and in Tennessee; by Prof. J. M.. 
AFFORD 
‘THE object of the following note is to point out briefly the 
- geological position of the ae reservoirs in Southern Ken- 
tucky and in Tennessee, so far as they have been met with 
within the field of my npeervecionk: I hope, in a future articl 
to give a summary of all ascertained facts with reference to the 
mineral oils of this re : 
The accompanying general section will serve to illustrate the e 
topographical and geological features of the region under consid- 
eration. The line of section extends from the Cumberland 
mountain, or table-land, in “Putnam county, Tennessee, through 
_Overton county, in a a direction a little west of north, to Burks- 
‘yille, Kentucky, and thence to Glasgow. The entire ‘distance is 
