INCUBATOR HOUSES AND CELLARS 327 
judgment, skill, and close attention of the operator. The next 
development of the artificial method was in France during the 
fifteenth century, but little actual progress was made. In the 
latter part of the eighteenth century water was first used as a 
means of supplying heat to the eggs, all preceding work having 
been done by heated air. 
In 1845 a self-regulating valve was invented, which regulated 
the temperature or reduced it when too high. This device opened 
the way and made possible the modern self-regulating incubator. 
The following year, in an attempt to imitate the natural method, 
a special apparatus was constructed to supply heat from above. 
There was no noticeable advance from this time until the last 
quarter of the nineteenth century when, owing to the increasing 
demand for poultry, largely because of increased population, much 
construction work was done in this country and abroad, resulting 
in many new and superior types of incubators. 
To Charles Cyphers belongs much of the credit for developing 
in America the commercial artificial incubator. While he was not 
by any means the first experimenter in this line, yet he accom- 
plished much, and made improvements which soon reduced the 
process to a practical science, and enabled any one of limited 
means to own and successfully to operate an incubator. Since 
1870 many improvements have been worked out, with the result 
that different models have been put on the market. Many of 
these are good structures of desirable type, but many, too, are 
faulty in design and poorly built, therefore cannot be expected 
to work successfully. The aim has been to construct an incubator 
which would be operated by any one, in any place, with the least 
possible care and oversight, and in great measure this has been 
accomplished. Yet in many important ways the incubator must 
be improved in order to make it as efficient as the hen. 
Incubator Houses and Cellars.—The successful operation of 
any incubator depends largely upon the place in which it is located, 
and the rapidity and ease with which the operator can secure and 
hold the desired temperature. Therefore, the design, construction, 
and location of the building or room in which the incubators are 
to be placed must be carefully considered. The requirements of 
the incubator room are briefly stated as follows: (1) Even tem- 
perature, (2) plenty of ventilation, (8) abundance of moisture. 
It must be possible to maintain in the incubator room approxi- 
mately an even temperature of any desired degree. Variation 
