The Drawing Instrument
If you are interested in collecting drawing and mathematical instruments, there are a number of very informative sites where collectors are sharing examples. This includes images of sets illustrating the development of drawing instruments from Georgian through to vintage examples. Huge amount of information - well worth a look if you are a collector.
A few of the very informative websites we have found are:
Please note that these are collector's sites - apologies if they have moved or been removed!
A shagreen cased set of early 19th century George IV drawing instruments c1835