with considerable reduction (^Friction. 151 
to the diameter of the wheel, than it is in that of Earnghaw. 
The other wheel, of which the diameter is almost double that 
of the impulse wheel, produces the pause to allow the regulator 
to accomplish freely its vibrations and its rests, by the extre- 
mity of its tefeth on the detent- spring. Since this wheel is of a 
much greater diameter than the impulse- wheel, it is evident 
that the pressure of the wheel work against the detent will be 
weaker than in the escapement of Earnshaw, when the same 
wheel serves for the impulses and the pause; by this diminu- 
tion of pressure, the friction of the teeth against the detent will 
be reduced, and the regulator will thus suffer less resistance ih 
disengaging the detent-spring from the stop-wheel. 
In Earnshaw’s escapement, since each tooth of the escape- 
ment-wheel has a double operation to perform during a revolu- 
tion, it must be made very thick, in order that the fine points of 
the teeth may not wear off. In the free escapement with a 
double wheel, where the teeth have only one operation, the 
wheels admit of being made lighter, so that their inertia will be 
reduced nearly to the same quantity as that of the single, but 
thicker wheel. 
The great reduction of friction, particularly at the escape- 
ment, will undoubtedly be of real advantage, since gentle fric- 
tions are always more constant than those which are heavy, that 
is less subject to be augmented, particularly in cases where the 
use of oil must be avoided. And it is this circumstance which 
gives us reason to hope that the escapement now proposed may 
contribute to the precision of chronometers. 
Art. XXV . — On the Formation of Valleys^ o>nd Creehs. 
By the Rev. George Young, M. A. Whitby. 
M R Young, in his valuable Geological Survey of the Coast 
of Yorkshire, just published, which we recommend to the, atten- 
tion of geologists, advocates that opinion which refers many of 
the inequalities on the earth’s surface to breakings and changes 
of position in the strata, and to denudations or washing away 
of large portions of the upper strata. In the following observa- 
tions, he shews how this mode of explanation harmonises with 
geognostical phenomena in Yorkshire. 
