62 
The Illustrated Book ol Poultry. 
difference is, that instead of withdrawing from three to six gallons of water, to be replaced by 
boiling every twelve hours, at the same periods the lamp under the boiler is lit for a short time, so 
as to convey more heat into the tank, the water in which is never renewed, beyond filling up 
now and then the trifling loss from evaporation. No evil result was found to follow such use of 
a lamp or furnace about the machine ; and it was at first believed this was merely because, during 
such a short time, the supposed injurious effects were not produced. But this opinion was upset 
by the undeniable success of the “ Patent Automatic Incubator,” brought out in 18S0 by Mr. 
Henry Tomlinson, the well-known Cochin breeder of Birmingham. 
This machine returns to the early principle of a lamp kept constantly burning, in conjunction 
with an automatic regulator, the latter being in its proper place — the egg-drawer. But an 
all-important lesson had now been learnt, Mr. Tomlinson having experimented with a water 
machine of the “Reliance” make. In his first pamphlet, published in 1880, he brings this 
out clearly, explaining how the points of construction above explained “ are equally important 
Fig- 3/A- 
Fig. 371?. 
in lamp incubators,” and that “ there is no reason why, because a fairly uniform and con- 
tinuous heat can easily be obtained from a good lamp, that the necessity of having a good 
reservoir of heat should be overlooked, . . . and I prefer in my lamp machines to use tanks 
nearly as large as those found necessary in the hydros. For the 100-egg machine I use a 
tank holding nearly fifteen gallons, and when this is once heated to the working temperature of 
170°, it will be found almost impossible to raise or lower the heat as much as five degrees by 
any probable irregularity in the working of the lamp, the water, in fact, acting as the balance-wheel 
of a watch, or the fly-wheel of a steam-engine.” In the pamphlet lately issued by the company 
which has acquired the patent, the same thing is clearly expressed. “ The water,” it is said, “ at the 
bottom of the tank, below the heating tubes, is not in circulation or motion to any considerable 
extent, and as water conducts heat but slowly downwards , it is not so hot as the water at the upper 
part of the tank, and is not readily affected by any change in the lamp. The large body of water 
in these machines holds the heat so well and steadily, that if the lamp should be accidentally put 
out for twelve or fourteen hours, the working of the machine would not be dangerously affected.” 
Such, then, was the grand secret, which can only be ignored by a machine that possesses a 
perfect regulator. The large body of water, heated more or less from above , and holding a steady 
heat, simplified the whole problem, and, it will be seen, is also strictly analogous to the larger 
chambers of Egypt. With such tanks, any passable regulators work well and easily, and the rest 
