Usage: Apparently used to demonstrate the effects
of total mass and center of mass in the determination of weight
using equal-arm balances.
According to John Russell (Professor, HSU Chem. Dept., 1956-92)
the device was a demonstrator provided to Mettler sales personnel.
It was obtained when Arthur Smith (Professor, HSU Chem. Dept.,
194869) requested it as part of a purchase of Mettler balances
by the Department in 1960/1. As far as he could remember it was
never actively used, except possibly by Dr. Smith. The box had
been in the back of a shelf in the stockroom for as long as anyone
could remember when it was discarded by the HSU Chemistry department
stockroom in 1992.
Description: The device consists of a gold anodized
Al upright column which screws into a threaded insert in the
front panel of the case, and which has a small right angle shaft
at the top. A turned black anodized hub equipped with ball bearings
fits over the shaft. Two Al rods screw into the opposite sides
of the hub, each is alternately banded in silver and black at
about inch intervals. Two pairs of anodized Al spheres (one red
and one blue in each pair), about 1.6 & 2.4 inches diameter,
thread onto the ends of the shafts. A gold anodized Al pointer
then screws into the top of the hub, while a black anodized "T"
screws in below to provide adjustments for center of mass (one
each slip-on (0.9") and threaded (1"), nickel-plated
brass balls) and balance (slip-on, spring-held, about 1.1 inch
blue anodized Al sphere). A gold anodized, quarter circle scale
clamps onto the shaft through a gold anodized extension. A small
(about 0.6 inch) blue anodized ball with attached short shaft
slips into a hole on the top of the large blue sphere to act
as a weight. The maximum overall dimensions of the assembled
apparatus are 15" wide by 15" tall, excluding the base.
The device is now mounted on a custom base of 1" thick
epoxy lab bench-top through a black Al pedestal threaded to fit
the column. The apparatus includes the original wood case fitted
with hardwood compartments contoured to the various components
(the hinges are missing and have been replaced with tape, but
the latches are present on either side, though rusty).
