A late 18th century set of drawing instruments by Dollond, London

A late 18th century set of drawing instruments in original black sharkskin covered case.
The set comprises:
Ivory protractor, engraved Dollond London
Ivory sector, engraved Dollond London
Ebony & Brass parallel rule
Large brass compass with interchangeable leg, complete with pencil, ink and divider attachments
Brass ruling pen with pricker in the handle
Small brass ink compass
Brass dividers with fine adjustment
Steel compass adjuster tool
The spare hole in the box is for a pencil.
Sold, as seen, in unrestored condition with the following faults:
Ivory sector damaged
Brass dividers – the adjusting screw is missing.
Steel knob to open case is missing