For
instance, the barometer-wheel carries successive numbers for every
five-hundredth of a millimeter--760.00, 760.05, 760.1, etc.; so that
when the motion is stopped the uppermost type gives in figures the
actual reading of the barometer. Then a subsidiary arrangement first
inks the types, then prints them on a slip of paper, and finally winds
the dipping wires up to zero again.
An ingenious apparatus prevents the electricity from sparking when
contact is made, so that there is no oxidation of the mercury. The
mechanism is singularly beautiful, and it is quite fascinating to
watch the self acting starting, stopping, inking, and printing
arrangements.
We could not but admire the exquisite order in which the whole
apparatus was maintained. The sides of the various glass tubes were as
clean as when they were new, and the surfaces of the mercuries were as
bright as looking glasses.
The university may well be proud that the instruments were entirely
constructed in Stockholm by the skillful mechanic Sorrenson, though
the cost is necessarily high.
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