of the hot bulb engine. His research culminated in an 1890 patent for a compression ignition engine. Production started in 1891 by Richard Hornsby & Sons of Grantham, Lincolnshire, England under the title Hornsby Akroyd Patent Oil Engine under licence. Stuart's oil engine design was simple, reliable and economical. It had a comparatively low compression ratio, so that the temperature of the air compressed in the combustion chamber at the end of the compression stroke was not high enough to initiate combustion. Combustion instead took place in a separated combustion chamber, the "vaporizer" (also called the "hot bulb") mounted on the cylinder head, into which fuel was sprayed. It was connected to the cylinder by a narrow passage and was heated either by the cylinder's coolant or by exhaust gases while running; an external flame such as a blowtorch was used for starting. Self-ignition occurred from contact between the fuel-air mixture and the hot walls of the vaporizer. 1887: William Thomson (later Baron Kelvin) of Belfast, Ireland introduces the multicellular voltmeter. The electrical supply industry needed instruments capable of measuring high voltages. Thomson's voltmeter could measure up to 20,000 volts. It could measure both direct current (DC) and alternating current (AC) flows. They went into production in 1888, being the first electrostatic voltmeters. 1887: Charles Vernon Boys of Wing, Rutland, England introduces a method of using fused quartz fibers to measure "delicate forces". Boys was a physics demonstrator at the Royal College of Science in South Kensington, but was contacting private experiments on the effects of delicate forces on objects. It was already known that hanging an object from a thread could demonstrate the effects of such weak influences. Said thread had to be "thin, strong and elastic". Finding the best fibers available at the time insufficient for his experiments, Boys set out to create a better fiber. He tried making glass from a variety of minerals. The best results came from natural quartz. He created fibers both extremely thin and highly durable. He used them to create the "radiomicrometer", a device sensitive enough to detect the heat of a single candle from a distance of almost 2 miles. By March 26, 1887, Boys was reporting his results to the Physical Society of London. 1887–1888: Augustus Desiré Waller of Paris recorded the human electrocardiogram with surface electrodes. He was employed at the time as a lecturer in physiology at St