Everybody is familiar with chainsaws nowadays. We associate them with cutting trees, carving wood, or with grislier applications such as those depicted in some horror films. However, the true reason why chainsaws were developed is far removed from the world of lumberjacks, woodcarvers, or slasher movie psychopaths. Chainsaws were developed to aid in childbirth and to facilitate surgeries that involved cutting bones! In the era before anesthesia, antibiotics, or knowledge about the role of germs in infection, when babies got stuck in the birth canal, C-sections were often fatal, so doctors figured out other ways to deliver the baby. For this they performed what is called a symphysiotomy. Towards the front of the body, the birth canal is surrounded by two bones (pubic bones) that are joined together by a joint made out of cartilage called the pubic symphysis. This joint is located above the external genitalia and in front of the bladder. In a symphysiotomy, a doctor would cut through this joint, thus widening the birth canal and allowing birth. In an era when surgery had to be performed very quickly to reduce risks of infection, symphysiotomy, although an improvement over C-sections, was still a risky and laborious procedure that was carried out with saws and knives. But in 1785, the Scottish doctors John Aitken and James Jeffray developed a cutting technique using a hand-powered fine serrated link chain that shortened the length of the procedure and improved its precision. Further refinements to the invention were made until the development of anesthesia and aseptic techniques by the start of the 20th century improved the safety of C-sections and rendered symphysiotomies obsolete. The first chainsaw bearing a resemblance to current chainsaws was made in 1830 by the German Physician Bernhard Heine. It consisted of a serrated link chain that was powered by a hand crank and was called the “osteotome”. The osteotome was used in surgeries that required cutting bone and was an improvement over earlier methods using hammers, chisels, and saws which left splinters and caused a lot of damage to soft tissue. Chain saws designed to cut wood were created at the beginning of the 20th century, and were modelled based on Heine’s osteotome, although they were bulky contraptions that had to be operated by more than one person. It would only be in the 1950’s that the first chainsaws operated by one person were made. Soon thereafter chainsaws began to be used for woodcarving as an art form. This art has evolved into a sophisticated activity featuring various styles, skill levels, and themes that are displayed in national and international competitions. The time-lapse video below was shot at the Montgomery County Agricultural fair in Gaithersburg, Maryland, and features the wood carving art of Joe Stebbing. The image of an osteotome is a private photo taken at Orthopädische Universitätsklinik Frankfurt by Sabine Salfer who has released it into the public domain.
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One Day I was going to wash the dishes that had accumulated in the sink, but when I turned on the water, something happened that is captured in the video below. Through sheer happenstance, the oven pan placed in the sink was balanced over other dishes in such a manner that when I turned on the water, it started cycling through filled and drained configurations. We had unwittingly created a relaxation oscillator! What is that? The term comes from electronics and refers to a circuit where flowing current charges a device such as a capacitor. Once the capacitor reaches a certain level of charge, it discharges and returns back to its initial uncharged state, only to be charged again by the current repeating the cycle. These oscillating circuits produce low frequency signals that are used in applications such as beepers and blinking lights. However, the term relaxation oscillator can be applied to any system which builds up energy and then releases it, just to build it up again with certain periodicity. One example of a relaxation oscillator is the Old Faithful geyser in Yellowstone National Park. And, as many of my readers have probably figured out by now, the particular relaxation oscillator in my sink has a more colloquial albeit less interesting name: tipping bucket. These contraptions are often found in water parks, works of art, and in applications such as rain gauges. |
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