The use of maths and angles is not immediately obvious as having a war like purpose, however when you look at the very technical branches of the military, such as the engineers or the artillery, the ability to very precisely calculate angles becomes essential. The artilleryman needs to set the elevation of his guns very precisely so that his shells land where he wants them to go and don’t overshoot and miss their target, or fall short and hit his own men. For the engineer, angles are essential for any form of construction. The use of protractors, therefore, has been of great importance for many centuries. By the early twentieth century, new materials such as early plastics allowed transparent mathematical instruments to be manufactured that were far simpler to use than instruments made of boxwood or ivorine that obscured the lines on a piece of paper. Today we are looking at a celluloid protractor from World War I:

Early plastics were very brittle and could shatter or crack easily, so this protractor is supplied with a sturdy cardboard case to protect it from damage, the case consisting of two very thick pieces of card, with paper tape pasted around three sides to make up a small wallet:

The protractor itself is circular in design, allowing angles from 1 to 360 degrees to be measured:

The date of 1918 is marked on the protractor, together with the manufacturer’s name. A small /|\ mark can just be made out below the markings, stamped into the plastic:

With these early plastics being so fragile, and susceptible to chemical decomposition or spontaneous self combustion it is remarkable that this example has survived the last 105 years and is still perfectly useable today.