The serial numbers for the Horace Waters pianos are

  1916  79,000
  1917  80,000
  1918  81,000
  1919  82,000

  Ref.: Pierce Piano Atlas

The use of rounded-off numbers would seem to indicate that these
numbers probably are not true indicators of the actual number of
pianos produced in any particular years.

Hal Davis

 [ I think that the 5-digit number is the first serial number of the
 [ year; they didn't anticipate making more than 1000 pianos per year.
 [ -- Robbie