The sunspot drawings of Johann Staudacher of 1749–1799 were used to determine the solar differential rotation in that period .
These drawings of the full disk lack any indication of their orientation .
We used a Bayesian estimator to obtain the position angles of the drawings , the corresponding heliographic spot positions , a time offset between the drawings and the differential rotation parameter \delta \Omega , assuming the equatorial rotation period is the same as today .
The drawings are grouped in pairs , and the resulting marginal distributions for \delta \Omega were multiplied .
We obtain \delta \Omega = -0.048 \pm 0.025 d ^ { -1 } ( -2.75 ^ { \circ } /d ) for the entire period .
There is no significant difference to the value of the present Sun .
We find an ( insignificant ) indication for a change of \delta \Omega throughout the observing period from strong differential rotation , \delta \Omega \approx - 0.07 ~ { } { d } ^ { -1 } , to weaker differential rotation , \delta \Omega \approx - 0.04 ~ { } { d } ^ { -1 } .