The chainsaw was invented for childbirth. In the late 18th century, two Scottish doctors created a small, hand-operated chain saw to help deliver babies during obstructed labor. The tool they designed bears little resemblance to the gas-powered machines used in forestry today, but the core mechanism, a toothed chain moving along a guide, is the same concept that eventually made its way into the timber industry over a century later.
The Medical Problem It Solved
Before modern cesarean sections became safe and routine, a baby stuck in the birth canal was a life-threatening emergency. One option available to surgeons was a procedure called symphysiotomy, which involved cutting through cartilage and bone in the mother’s pelvis to widen the birth canal enough for the baby to pass through. In the 1780s, this cutting was done with basic hand tools: knives, saws, and sometimes hammers and chisels. These instruments were imprecise, difficult to control, and made an already dangerous situation worse.
Cesarean sections did exist at the time, but they carried an extremely high mortality rate for mothers. Even as the surgery improved in later centuries, it came with limitations. A woman who had one cesarean delivery was likely to need cesarean deliveries for all future pregnancies, and medical practice generally capped the number at three. For these reasons, surgeons continued searching for better ways to assist vaginal delivery when complications arose.
Who Invented It
Two Scottish doctors, John Aitken and James Jeffray, developed the prototype in the 1780s. Their design appeared in the 1785 medical text “Principles of Midwifery, or Puerperal Medicine,” where it was described as a “flexible saw contrived to be used when there is ossification,” meaning obstructive bone blocking the birth canal. The tool was designed specifically for symphysiotomy and for cutting away diseased bone. It was small enough to use in tight surgical spaces and operated entirely by hand.
The chain of fine, serrated teeth could be wrapped around bone or cartilage in areas where a straight saw simply wouldn’t fit. This flexibility was the key innovation. A rigid saw required room to move back and forth, but the chain saw could work in the confined space of a pelvis during an obstructed delivery.
How Bernhard Heine Improved the Design
In 1830, German surgeon Bernhard Heine took the concept further with a device he called the osteotome. This was a hand-cranked medical chainsaw built for orthopedic surgery. Before Heine’s invention, surgeons performing amputations and bone surgeries relied on hammers, chisels, and hacksaws, all of which required brute manual effort and produced wildly inconsistent results. The uneven force could cause additional injuries, severe bleeding, and extreme pain for the patient.
The osteotome changed this by mechanizing the cut. A hand crank drove a chain of identical teeth around a guide rod, giving the surgeon consistent cutting force. The surgeon could use body weight to assist with pressure while the guide rod controlled placement. Despite looking nightmarish by modern standards, it was significantly less painful than the alternatives. Its small size and mechanical precision made it the first truly reliable cutting tool in orthopedic surgery, and it remained in use for decades.
From Operating Rooms to Forests
The leap from surgical tool to industrial machine took well over a century. The timber industry adopted mechanized chainsaws in 1905, borrowing the basic chain-and-guide principle but scaling it up dramatically. The first electric chainsaw came in 1926, patented by Andreas Stihl in Germany. It weighed about 64 kilograms (roughly 140 pounds) and required two people to operate, with handles at either end. In 1927, fellow German inventor Emil Lerp built the first gasoline-powered chainsaw, and Stihl followed with his own petrol version in 1929, which he called the “tree-felling machine.”
These early industrial chainsaws were enormous, impractical by today’s standards, and looked nothing like the surgical instruments that inspired them. But the underlying idea, a looped chain with cutting teeth driven along a bar, traces directly back to what Aitken and Jeffray built for use in a delivery room in the 1780s. The chainsaw spent its first 120 years as a medical device before anyone thought to point it at a tree.