Harrington's clockwork dental drill, the "Erado", in fitted case, no.124, 1864-1870

This dentistry tool, known as ‘Erado’ – or ‘I scrape out’ in Latin - was invented by British dentist George Fellows Harrington in 1864 to improve the method of removing tooth decay. It was a drill run by a clockwork mechanism, running for 2 minutes after being wound-up. This meant the drill could continuously rotate, improving the speed of the procedure. Harrington improved his design, introducing interchangeable heads and contra-angle handpieces – which meant the tool could be used at a more accessible angle to the patient.

However, the success of the drill was short-lived. It was noisy and awkward to control and was quickly overtaken by the invention of the foot engine in 1872. American dentist James B. Morrison (1829-1917) utilized the foot operated mechanism of a treadle sewing machine to create a foot operated drill which could achieve 2000 revolutions per minute (RPM). This technology was also overtaken once the first electric dental drill was patented, in 1875 by George Green.