DEEP-SEA EXPLORATION. 
277 
valve cbest and cylinder are cast in one, and tlie steam and exhaust pipes slide through 
stuffing-boxes; the cylinder is connected by the rod e to the throttle-valve lever. 
The action of the machine is as follows: The water, rolling from underneath the 
stern, causes a diminution of the pressure in the air-chamber, which is transferred to the 
mercury-cup, lifts the float and rod c, and, through the levers, communicates a definite 
amount of motion to the valve; steam is thus admitted to the cylinder and moves it to 
the right until its motion has equaled that of the valve, when the ports are thus 
automatically closed and the cylinder and throttle- valve come to rest. By changing 
the quantity of mercury iu the cup, adjusting the length of the rods or throw of the 
levers, the throttle-valve can be made to come to rest at any desired position, or to 
work between desired linuts. In practice the machine works admirably. 
BAIRD’S PNEUMATIC INDICATOR. 
It is well known that the inertia of a steam vessel in motion is considerable, and 
that it requires some little time to change her direction even aftei' the engines are 
reversed, and it often occurs in sounding and dredging that opposing winds and 
currents carry the ship from the desired position with reference to sounding wire, or 
dredge rope; hence it becomes imperative for the officer in charge to know promptly 
whether the engines are running in the right direction. The object of the indicator 
is to give him this information, also to show whether they are going fast or slow, or 
standing still. 
There is an indicator for each shaft, and, having twin screws, the Albatross has 
two. Cut 13 is a sectional view of the back, cut 14 of the side, and cut 15 is a view 
of the face; cut IG is a sectional view of the side, and cut 17 the end of the blower 
for the indicators; cut 18 is a general view of the indicator and its connections. 
