Level - E R Watts

Edwin Watts established his company in 1856 and it was incorporated as a limited company in 1919.
I cannot find any dates for the period for the name "E. R . Watts and Son".
Reference to Kilpatrick and Co in " Scientific Instrument Makers and Dealers in Victoria 1840 -1914" ( by H.C.Bolton and Nicola H. Williams) advises the latest date listed as 1898.
This level was based on a 1917 patent and from the stickers in the box was sold in January 1921 by Kilpatrick and Co.
The serial number is 7880.