Dividing engine

For every improvement in the measuring instruments, such as better alidades or the introduction of telescopic sights, the need for more exact graduations immediately followed.

In early instruments, graduations were typically etched or scribed lines in wood, ivory or brass.

This skill and knowledge seems to have been lost, given that small quadrants and astrolabes in the 15th and 16th centuries did not show fine graduations and were relatively roughly made.

Brass was in hammered sheets with rough surfaces and iron graving tools were poor quality.

These beam compass techniques were used into the 19th century, as the dividing engines that followed did not scale up to the largest instruments being constructed.

While beam compass use was critically dependent on the skill of the user, his machine produced more regular divisions by virtue of its design.

[3][4] This engine was developed with funding from the Board of Longitude[1] on condition that it be described in detail (along with the related screw-cutting lathe) and not be protected by patent.

In fact, the Board required that he teach others to construct their own copies and make his dividing engine available to graduate instruments made by others.

[1] In France, Étienne Lenoir created a dividing engine of greater accuracy than the English version.

Mégnié, Richer, Fortin and Jecker had also built dividing engines of considerable quality.

[5] The dividing engine was unique among developments in the manufacture of scientific instruments, as it was immediately accepted by all makers.