46 G. W. Hough on an Automatic printing Barometer. 
without being cleaned ; it being only necessary to add a little 
sulphate of copper and water from time to time, to supply the 
necessary waste. The only power demanded of the electro- 
magnets is the aulcekiiey of the mechanism, which is driven by 
weight power. 
In fig. 1, we have 1 
a sectional view of 
the lower leg of the 
siphon, showing the 
principle on which 
this method is based. 
not occupy these po- 
sitions in reality, but 
are placed here for 
convenience of illus- 
tration. 
Let B = battery. 
“ m,m'=electro- 
magnets | 
tf a’ = wheels B 
eccicn one tooth, and 
revolving in the di- 
rection of the arrows. bes 
aise > screw fe dace oe 
carried by the float 8. 
‘Thetwo wires, p, p’ 
are respectively above 
were below the center 
of the disk d. 
w= ee with 40 teeth in which is inserted the screw S. 
n = a small steel wire passing through the brass cap c, to pre ; 
vent the disk d from revolving. 
e = an ivory disk inserted in the tube, to prevent the float o 
be. 
from rubbing against the sides of the tu 
_ Now suppose the mercury should rise in the short leg of the 
siphon, as represented in the figure. The float 5 ne be raised, — 
and cause the platinum disk d to come in contact with the point 
of the platinum wire p, closing the circuit ceteuaty the trae : 
magnet m; the armature of which being attracted, unloc 
Geiss 5 Wipes. aee oot 
i: rs 
eR EPA cic tairy! aie eta bk ORR arty Ptr pk 3 A 
