,54 Mr Murray’s Improved Apparatus for 
ral respiration. When the index points in the direction of the 
lungs, or parallel with the pipe, the communication between the 
lungs and cylinder is open ; and when at right angles, that with 
the lungs is shut, and the cylinder then communicates only with 
the free atmosphere. Hence, when the piston-rod is raised, and 
the index points to the lungs, the canal being open, the air re- 
posing on the lungs passes to the cylinder ; and when the index 
is movfed the quadrant of a circle, or at right angles with the 
former position, the aperture which leads to the lungs is closed, 
and that which conducts into the free atmosphere uncovered; con- 
sequently, on the descent of the piston-rod, the air drawn from 
the lungs is expelled into the atmosphere, while a fresh supply 
is received on elevating the piston ; and the index being turned 
into its former position, the descending piston propels it into the 
lungs, and the alternations of its movements assimilate to the 
beautiful isochronism of natural respiration, which is not very 
variable in health, unless affected by adventitious circumstances ; 
for a pendulum vibrating seconds may be its measure. To 
the lateral aperture is attached a concave pan, C, somewhat re- 
sembling that of a musket, to receive a drop of ether , which, en- 
tering into the cylinder along with the ingress of atmospheric 
air, expands and diffuses itself therein on the elevation of the 
piston, and thus operates on the lungs with all the stimulus of 
nitrons oxide. In cases of asphyxia by carbonic acid gas, a drop 
of ammonia may be serviceable, while, in that of the septic 
poison, sulphuretted hydrogen, a solution of chlorine might prove 
of benefit. D is the orifice by which the partition is supplied 
with heated water. 
Fig. 3. exhibits a section of the apparatus, where A is the piston- 
rod, accurately adapted to the cylinder in which it moves. This 
inner cylinder has one concentric with it which forms a partition, 
the recipient of the heated water ; and the base which limits the 
descent of the solid plunger, has a simple aperture without any 
valve . B is a toothed quadrant attached to a lever, and mov- 
ing on a fulcrum, for the purpose of elevating and depressing 
the piston. C is a check which regulates the altitude of the pis- 
ton ; and thus apportions its elevation to the capacity of the 
lungs, whether the subject be an adult or of tender age. D is a 
partition surrounding the inner cylinder, and supplied with wa- 
