70 
POPULAR SCIENCE REVIEW. 
Surveying and Levelling Instruments. — Mr. G. H. Birkbeck , 
patentee. — This invention has for its object the arrangement and combina- 
tion of parts so as to form a compound surveying instrument, called 
a 44 level-graphometer square,” which is capable of executing the various 
operations which each of the above-named instruments is only capable of 
performing separately. This improved instrument is composed of a 
cylinder of brass, or other suitable metal, divided longitudinally with its 
axis into two equal parts, connected together by a central pin or axis, 
thus forming two cross-staffs, to each of which 44 pinicles ” are hinged, 
so as to fold down out of the way when not in use. Between the two 
semi-cylindrical parts a dial or plate having divisions thereon is fixed and 
used. When the instrument is employed as a 44 grapliometer,” it is 
mounted, by a screw-pin or otherwise, upon a suitable stand or support. 
When the instrument is employed as a level, it is suspended by a ring 
attached to the upper end thereof, and is accurately adjusted perpendicu- 
larly by a movable weight, actuated by an adjustable screw attached to 
the lower end. Sight-holes or openings are formed through the movable 
semi-cylindrical part of the instrument, through which the divisions on 
the dial-plate may be seen and read off when required, a fine wire or 
thread being stretched across each aperture in the direction of the line of 
sight. Flat plates, connected by a central pin or axis, may be substituted 
for the semi-cylindrical parts before described, by which the construction 
of the instrument will be simplified, but its form will not be so elegant. 
The divisions on the dial-plate are in sections of five, or other suitable 
number of degrees, so that the instrument acts not only as a 44 square,” 
but also admits of small angles being taken, as with the 44 graphometer.” 
Barometers or Instruments for Measuring Altitudes, or the 
Pressure of the Atmosphere, &c. — Mr. J. E. Blackwell , patentee. — 
This invention relates to a novel mode of constructing these instruments, 
so as to render them portable, and exceedingly sensitive and accurate. 
These objects are effected in some of the improved instruments by a com- 
bination of several separate improvements ; but, in others, some only of 
the improvements are comprised. In all the improved instruments, 
however, the variations in pressure are ascertained by means of elastic 
vacuum chambers, as in the ordinary aneroid barometer ; and the patentee 
finds it convenient to employ four or more elastic chambers arranged in 
groups or sets, so that the inequalities of pressure, or inaccuracies of 
action in any of the several chambers, shall be compensated by the others. 
In all the instruments these vacuum chambers are directly attached to 
or connected with helical or other springs, the power or elastic force of 
which has been previously ascertained with great care, and which recipro- 
cate the expansion or compression of the chambers accordingly as they 
are acted upon by diminished or increased pressure. 
Watches. — Mr. F. B. Anderson , patentee . — This invention consists in 
constructing those parts of watches and other time-keepers known as 
hollow fusees, and as stops to prevent the main-spring from being over- 
wound, as hereafter described. The patentee forms a disc on the arbor, 
by preference, in a piece with it, and sinks a recess in the outside of the 
fusee brass, into which the disc is fitted and secured by soldering or other 
