26 
The Australasian Book of Poultry. 
is due to the regulator, and not the air or water. Taking all things into consideration, I would prefer a hot 
air machine, for the simple reason that one is not troubled with leaks, rusting of the tank, freezing, and, last 
but not least, bulging of the tank from the weight of the water. But, you say, hot water circulates freely in 
the tank, and hot air takes the nearest path to the outlet pipe, and leaves the corners comparatively cool. 
That is true in a measure, but this fault may be overcome in the following manner. See Fig. 19. Place 
two partitions in the tank, each one lacking about two inches from reaching the opposite end, and those 
ends on opposite sides, and you will compel the hot air to travel all through the tank before it escapes. 
This requires a little time, and, as a consequence, the air imparts the greater portion of its heat to the tank. 
As to the regulator, I must admit that most of them are unreliable ; but I am prepared to back up this 
statement with facts, all regulation depends upon the expansion and contraction of a thermostat as its 
motive power. Some of the thermostats are metal, others of rubber, or a composition of rubber. Now, this 
principle is mechanically incorrect. Suppose, for argument, we take a rubber tliermostat, which is pivoted 
to a balance bar, which raises and lowers the lamp flame ; suppose, again, that this will e.xpand one-eighth of 
an inch to a rise of two degrees of temperature. Now temove the attachments from the thermostat, so as to 
leave its end free to expand without resistance, you will find it expand one-fourth of an inch, instead of 
one-eighth, thereby showing that its expansion was interfered with by the resistance of the regulator. The 
result is, that this resistance will condense or stretch (according to the plan of attachment) to such an extent 
as to render the thermostat very feeble or useless. This will not take years, but days. A metal thermostat 
is much worse than a rubber one, as the metal soon becomes rusty, and the continual heat gradually 
removes the temper. In this connection I should like to revive an old friend who was buried long ago, and 
died because he was not properly understood — Electricity : The electric regulator of our old-style 
machines was simply awful. Mechanically, the clockwork motor, ihe thermostat and the commutator and 
battery were a nightmare to the Poultryman. You could depend on one or the other getting out of order in 
the middle of every hatch, and as the average Poultryman is a poor electrician, it meant a spoiled hatch ; 
but, in spite of this, I am going to submit to you an electric regulator which anyone can make, and which 
can be attached to any make of Incubator. Fig. 20. A A are a pair of electro-magnets. B is an iron 
armature attached to the balance rod C, D is a forked iron support, with knife edges for balance rod, E is 
the end of the thermostat, F is a piece of iron through which a screw is run, to be moved backwards and 
forwards so as" to regulate the electric contact with the thermostat. The wires are run as follows : — From 
magnet A to the thermostat, around which the wire is wrapped ; from the other magnet A to battery, from 
battery to set screw in F. Now, the operation is thus : The balance rod is so weighted that it naturally closes 
the lamp flue, and the armature is raised above the magnets. When the temperature rises the thermostat 
expands and touches the set screw F. This closes the circuit. The magnets draw down the balance rod 
and open the lamp flue. When the temperature falls the thermostat leaves the set screw F, opens the 
circuit, and the bar falls, by its own weight closing the lamp flue. 
To regulate, permit the temperature to rise a small fraction above 103 degrees Fahrenheit, and then set 
the screw F so as to touch the thermostat. The action of this regulator is perfect, for the reason that it is 
instantaneous. Four cells of gravity battery should be used, and those will be sufficient to run three 
t 
Fig. 19. 
Fig. 20. 
