A History of Deceit

Since imagination first bloomed in humans so did the ability to deceive. Without imagination how would you be able to tell aunt Primrose that there were no cookies in the cookie jar? That at the very least requires a little imagination. When Murdoch set out to scientifically determine if someone was lying he acknowledged that,

“This is hardly the first lie detector. African tribes used to pass around a bird’s egg to measure nervousness, ancient China used rice to gauge saliva flow”

Although there is only once source for this it seems plausible that in West Africa a group of people, including the suspect would pass around an egg and whomever broke it was guilty. Being nervous affects your dexterity making handling fine objects difficult. In Ancient China when questioned you would have a handful of dry rice in your mouth and if you could spit it all out then you were not guilty. This is because the Chinese believed that you produced less saliva when you were nervous, thereby making it harder to spit out the rice at the end of questioning. Finally the most interesting method and was the Ancient Indians. They would put oil or soot on a donkey’s tail and put him in a dark tent. They would then tell the suspects that the magic donkey would make a noise if he was touched by a thief and that they have to rub their hand down its tail. Take a moment and think what you would do if you were the thief. Chances are you wouldn’t want to touch the magic donkey, but if you didn’t you would have fallen for their trick. The people who are not guilty would touch the tail and have dirty hands but the thief’s hands would be clean.

Hydrosphygmograph – Look framiliar?

As we’ve learnt in the previous post, there are four components to the modern polygraph, the heart rate monitor, the blood pressure monitor, the pneumograph, and the galvanometer. The first component to be invented in 1895 was the Hydrosphygmograph by Cesare Lombroso which measure both blood pressure and pulse.  The next part, the galvanometer was invented in 1879 by Dr. Marie Vigouroux. The first use of the pneumograph to detect lies was in 1914 by Vittorio Benussi where he used the inspiration-expiration ratio to determine truth. John Larson was the first to put all four of these together to get the modern polygraph in 1921 at the University of California. On a strange side note Larson was born in Nova Scotia just like Murdoch. It was called a polygraph because it incorporated many different technologies and wrote them out, the real meaning is many copies and you can see from the picture below that this other polygraph had nothing to do with lying. Another figure worth mentioning is Leonard Keeler, who was the biggest proponent of the polygraph. If it were not for him the polygraph might not be as widely used today as it is not to mention he vastly improved on Larson’s design by adding the galvanometer working out kinks in the graphing process. Finally, today the old analog readouts have been replaced with digital ones but most of the equipment has remained unchanged. Also, some scientists are proposing the use of brain scans to detect a lie because, like I said at the start a lie requires imagination and that is a different part of the brain then recall. Stay tuned for a breakdown of Murdoch’s Night Vision Goggles.


Still a Lie

In the 19th century the idea of a device that could detect how truthful a person is was pure fantasy. More than a hundred years later, everybody know about lie detectors but not how they work. The name lie detector is somewhat of a misnomer, because they do not detect lies but instead monitor the physical response to questions. These modern lie detectors are called polygraphs and are comprised of four components, a galvanometer, a pneumograph, a blood pressure monitor, and a heart rate monitor. The galvanometer is used to measure moisture, the more moisture, the more the person being interviewed is sweating. This is done by connecting conductive pads to the tips of fingers and sending low voltage electricity to measure how much the skin resists the electrical charge. The more resistance, the less sweat is present. A pneumograph measures respiration by using tubes attached to the chest. As the chest moves air is displaced and you can convert this displacement into mechanical movement. The sphygmomanometer restricts blood flow, usually through the arm, and then measures the pressure pushing against the restrictor. Finally the last component, the heart rate monitor. The heart rate monitor uses the sound of blood being pushed through the veins to monitor how fast the heart is beating. In Murdoch’s machine he only used one of these components.

In the episode “Still Waters”, if you listen carefully Murdoch call his invention a pneumograph. It is obviously similar to the modern day component of the polygraph but instead of the bellows that pushes air and moves the arm or creates the electrical signal, Murdoch used water. Water has this neat property that it’s incompressible which means that no matter how much pressure you put on, the volume of water barely changes.  (a neat demonstration of this is fill a plastic bottle with water and you can use it as a hammer. Please use plastic glass could get really messy). As the wear of the pneumograph inhales the the liquid gets pushed out of the tube and up into the condenser. This would allow you monitor the rate of breathing, but for the blue liquid to move up the tube as the breathing rate increases.Murdoch would of had to add a valve that allows the water to to drain at the average respiratory rate which is about 12-20 breaths per minute times the average amount of water displaced by a single breath. This would have to be calibrated for each person to be accurate. 

I am dubious of how well this would work, from personal experience I find that it is much easier to control my breathing than it is my heart rate. This is one of the reasons a polygraph uses all four sensors to measure physiological changes. In defense of Murdoch’s lie detector just the mere idea that it detects lies will help discover if the suspect is lying because there is increased pressure on them when they lie, so they more likely be detected . Finally, Inspector Brackenreid alluded to the fact that courts usually won’t take polygraph tests as evidence. This is because they can be wrong, there is no arrow that flips from telling the truth to lying and because of such, they are subjective and you don’t want to be convicted on someone’s interpretation of a polygraph. Stay tuned next week for a brief history on lie detectors.

If you have not seen Still Waters, in the first season of Murdoch Mysteries, it contains one of the best scenes in Murdoch when he is hooked up to his lie detector.

Wireless Electricity

Right now you are looking at one to the most impressive displays of electricity that has ever existed, millions of separate electrical systems all working together for you to be able to read this. For Murdoch this demonstration was a surprise as he picked a light bulb in Nikola Tesla’s lab and it lit up all by itself.


“You’re standing in a high frequency electrical field.”

“That’s how a light bulb can be powered without wires…”

Wireless electricity is not a new concept, it has been around since 1831 with Michael Faraday. Sixty years later Tesla patents a way of efficiently producing high-power radio frequencies and goes on to light a light bulb wirelessly. It is even used today in the tap-to-pay credit cards and access cards and even in the loss prevention alarms at store exits. The best way to illustrate this is though electrical transformers.

The most common use of transformers are by power companies transporting electricity. This is because it is much more efficient, less power is lost, when electricity is transmitted at high voltages. Since North America standard household voltage is 120 volts, the voltage needs to be stepped down from the thousands of volts that is coursing through the high voltage lines. To do this the transformer has a magnetic core with two coils, the high voltage current is connected to the primary coil and the household circuit connected to the secondary coil. As current is passed through the primary coil it creates a magnetic field. This is the same principle that powers electromagnets. The opposite happens when a magnet is passed by a coil, it induces a current by pushing the electrons through the coil. Now that the primary coil is creating a magnetic field the secondary coil is having its electrons pushed through it and it creates an electrical current. Depending on the number of wraps, depends on the number of wraps compared in the primary coil compared to the secondary coil.

Transformers are extremely useful but for wirelessly transmitting power they are a bit disappointing because they are physically connected by the core. They do however form the basis for a wireless transmitter with a longer range. There is still the primary and secondary coil, but this time we need them to resonate at the same frequency. It is the same principle as tuning to your favorite radio station, when you turn the dial, or I guess nowadays digitally tune, to a certain frequency, your radio is resonating with the radio station’s broadcasting transmitter. Once these two coils are resonating, the same thing happens that happened in the transformer, the magnetic field is pushing electrons through the secondary coil but instead of the solid magnetic core the core is air.  The problem however is that like radio waves, they get weaker as you get further away (by a factor of one over the distance cubed) and that the power transfer is not 100 percent efficient and that a lot of power would be wasted.

You can learn more at the Wireless Power Consortium’s website under technology. There are also a few do-it-yourself wireless electricity experiments that you can find on your favourite search engine. I will do a follow up if I ever get around to making one. So stay tuned for Thursday to see if I’m lying.

The wireless power was featured in the first episode of Murdoch Mysteries, Power, I would highly recommend it if you have not seen it. You can find it on Netflix or Amazon for 2.99.


Toronto ElectricMurdoch Mysteries is a Canadian TV series set in the late 19th century. It features Detective William Murdoch who is fascinated by the rapid scientific advancement of his time. He applies many forensic techniques that we would consider modern and pushes the boundaries, sometimes by decades, of scientific invention. My goal is to try and capture some of the genius that went into the creation of some of the inventions. Depending on the subject I will give a little background and show where on the timeline Murdoch’s invention came into being relative to the actual invention. I will also give an explanation on how I think Murdoch’s invention works and the science behind the modern counterpart. I will do my best to update every Tuesday and Thursday from here on out. Stay tuned for Tomorrow’s dive into the world of wireless electricity.