Some of the bee supply firms sell a simple hive scale.  An arm extends up
by the side of the hive, as the hive increases in weight, the arm moves
across an arc (kind of like a sundial) and the weight can be read.
Relatively inexpensive, but probably as accurate as bathroom scales, which
we found to be poor out-of-doors.  The mechanical ones rust up, the
electronic ones fail rapidly.
 
Jerry Bromenshenk
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