Rev. W. Hodgson’s Description of the Chronoscope. 269 
the other; but a difficulty arises in narrowing the circle. 
On the one hand, it seems quite impossible to trace the 
four African races to any part of Asia; and, on the other, 
it will be equally difficult to connect the Mongolian race 
with the African continent. 
Description of the Chronoscope, an instrument proposed for 
jinding the Time by Observation, and thence deducing the 
Latitude and Longitude of the place of the Observer. By 
the Rev. W. Hopeson, Old Brathay, Ambleside. Com- 
municated by the Author. 
Srr,—As the importance of ascertaining correct time is 
generally acknowledged by both scientific and practical men, 
probably little apology is necessary for introducing to your 
readers some particulars relative to a simple double-altitude 
and meridian-instrument, which will accomplish that object 
without requiring either the latitude or longitude of the place 
of observation, or any graduated circle, or any assistance 
from any observatory, or anything beyond a plumb-line and 
a watch of uniform rate. 
The instrument is susceptible of several different forms. 
Of these, perhaps, the most commodious may be described as 
a right rhombic parallelopiped of glass, formed by a pair of 
equilateral triangular prisms, with two of their faces in con- 
tact, and with their axes parallel to each other. The brass 
frame, on which the prisms are mounted, covers about one- 
third of each of their faces at the parts where they are in 
contact, 7. e., at the greater angles of the rhomb, and is 
fitted (either in the same way as the reflector of an ordinary 
microscope, or by some other similar plan) so as to allow the 
instrument to be moved at pleasure on either of two planes, 
which are perpendicular to each other. These planes being 
respectively parallel and perpendicular to those faces of the 
prisms which are in contact. 
If the instrument thus described be clamped to a post-foot or 
