Dou"bler (?), n.
1.
One who, or that which, doubles.
2. (Elec.)
An instrument for augmenting a very small quantity of electricity, so as to render it manifest by sparks or the electroscope.
© Webster 1913
Dou"bler (?), n.
1.
A part of a distilling apparatus for intercepting the heavier fractions and returning them to be redistilled.
2. (Calico Printing)
A blanket or felt placed between the fabric and the printing table or cylinder.
© Webster 1913