turboscience

A sensitive beam balance

 The materials needed for this balance include a clothes peg, a knitting

needle about 12 in. long, two pins or needles and a support such

as a milk bottle or preserving jar.

 The beam of the balance is made by passing the knitting

needle through the hole in the spring of the clothes peg.

The pivots for the beam are the two needles or pins

placed one on either side of the clothes peg, slightly below

the hole through which the knitting needle passes. The

latter must project equally on either side of the clothes

peg, and can be wedged in this position inside the spring

by a small splinter of wood. The lower end of the clothes

peg grips a pencil which serves as the pointer of the balance. The pans of the balance are made from two tin

lids pierced at the circumference by the equally spaced holes through which threads are passed and tied

together to form a loop from which they can be suspended from the beam. Once the scales are balanced it

is advisable to make a nick with a file to prevent the loops slipping off the knitting needle. Finally a

graduated scale is placed inside the bottle in such a way that the pointer swings in front of it.

 The weights may be coins, crown corks, matches, etc., correlated to standard weights. If none of the

latter are available two similar small bottles may be used, one in each pan, and known amounts of water

poured into one of them from some graduated vessel. Failing all else an old novocaine tube used by dentists

for local anaesthetic is graduated in cubic centimetres and may serve as a very small measuring cylinder.

Fractional weights may be improvised by hanging a loop of wire from the beam.