Why Was the Chainsaw Invented?

The first chain saw was a surgical instrument. In the 1780s, Scottish physicians John Aitken and James Jeffray built a flexible saw — a fine serrated chain with a handle at each end — to cut through the pelvis during symphysiotomy, a procedure used when a baby could not pass through the birth canal.

The timber chainsaw descends from that instrument, but through a longer and messier chain of hands than the internet version suggests.

The procedure it was built for

When a baby was too large for the mother’s pelvis, obstructed labour could kill both. Before caesarean section was survivable, one option was symphysiotomy: cutting through the pubic symphysis, the cartilage joint at the front of the pelvis, to widen the outlet.

Surgeons did this with a knife and a rigid handsaw. It was slow, imprecise, and frequently damaged the urethra and bladder. It was also performed without anaesthesia — ether and chloroform did not enter surgical use until the 1840s, some sixty years later.

The problem Aitken and Jeffray set out to solve was not how to cut bone. It was how to cut bone quickly, inside a confined cavity, without destroying what surrounded it.

A chain instead of a blade

A flexible serrated chain with a teardrop handle at either end could be threaded behind the bone and drawn back and forth, cutting from within the cavity outward. A rigid saw needs room to swing. A chain needs only room to pass.

Jeffray, professor of anatomy at the University of Glasgow, said the idea came to him from the jointed chain inside a watch.

Attribution here is genuinely unsettled. Sources place the work between 1780 and 1785, and the Royal College of Surgeons of Edinburgh has noted it is unclear whether the two men collaborated or arrived at the design separately. Jeffray is credited by some with the invention outright and by others only with recommending its use for joint excision.

It did not work especially well. Hand-powered speed proved inadequate for compact bone, symphysiotomy never became widely adopted, and the saw was soon repurposed for removing diseased bone and excising joints.

Heine’s osteotome

In 1830, the German orthopaedist Bernhard Heine (1800–1846) built the chain osteotome. Heine had been apprenticed around the age of ten to his uncle, Johann Georg Heine, as an orthopaedic mechanic in Würzburg, and he designed and built his own instruments throughout his career.

His device is the one that genuinely resembles a chainsaw: an endless chain running around a guiding bar, driven by a hand crank. He fitted guards along the edges so the chain could cut bone without tearing soft tissue, which made it usable for craniotomy — opening the skull without driving bone splinters into the brain.

Chain, guide bar, crank, guards. Every one of those is on a modern chainsaw.

The patent that connects the two

On 17 July 1903, Samuel J. Bens of San Francisco filed an application for an “endless-chain saw.” It was granted on 17 January 1905 as US Patent 780,476, with two-thirds assigned to John S. Kimball of Oakland.

The claims describe a chain saw with a bar-frame lying wholly within the cutting plane, supporting wheels at each end, and a handle extending beyond the cutting range. A thin steel frame with grooved edges; a guide wheel journalled at one end and an adjustable tensioning wheel at the other; individual saw teeth with tapered shanks seated into slots in each link, removable one at a time. That is a chainsaw. It was drawn in 1903.

Bens’s stated object was crosscut sawing, work then done almost entirely by hand. Figures 6 and 7 show the saw mounted on a portable skid with an engine geared to the drive wheel, cutting a redwood stump — material, he noted, ordinarily left standing because sawing it by hand was not worth the labour.

He was also not the first to file under that name. An earlier US patent titled “Endless-chain saw,” number 226,774, was granted on 20 April 1880 — twenty-five years before Bens.

None of this breaks the medical link. It relocates it. The mechanical idea moved through the nineteenth century in both surgery and sawmilling at once, and the honest description is convergence rather than a single line of inheritance.

Bens’s saw was far too large to carry. James Shand, a Canadian millwright, patented a portable version in 1918, then let his rights lapse; the German firm Festo, now Festool, developed the design further from 1933.

What the meme gets wrong

The version circulating online is that chainsaws were invented for childbirth, illustrated with a modern petrol saw.

The origin claim is accurate, and archivists at the Royal College of Surgeons of Edinburgh have confirmed the surgical hand chain saw was devised for use in childbirth. What the image distorts is scale. These were hand-held, hand-cranked instruments closer to a wire garrotte than a power tool. Medical archivists describe the Aitken design as an obstetrical prototype of the chainsaw — a statement about lineage, not equivalence.

The distance is also longer than implied. Roughly 120 years and four or five separate inventors separate Aitken’s saw from anything a logger would recognise.

Andreas Stihl patented the “Cutoff Chainsaw for Electric Power” in 1926 — the first electric chainsaw, weighing 64 kilograms and requiring two operators. His petrol-driven “tree-felling machine” followed in 1929, two years after Emil Lerp, his former business partner, had built the first petrol chainsaw and founded Dolmar to manufacture it. Stihl produced the first one-person chainsaw in 1930 and was exporting to the United States and the Soviet Union by 1931.

Symphysiotomy, meanwhile, was largely abandoned as caesarean section became survivable through better hygiene and anaesthesia. The procedure has a difficult modern history of its own in several countries, and the tool tends to be remembered as a horror-story fact rather than as the serious attempt at reducing harm that it was.

What stayed in medicine

The flexible chain saw never left surgery. The Gigli twisted-wire saw, built later on the same principle, is cheap, compact, and still used for bone cutting and amputation where precision matters and space does not exist.

Both lines continued. They simply stopped being the same tool.