Historical patent · 1965
A three-dimensional reconstruction of the machine patented by George B. and Charlotte E. Blonsky: mechanical architecture, rotational motion and an extraordinary idea from twentieth-century engineering.
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01 · The patent
One of the most unusual patents of the twentieth century and a case study of inventions that never reached the market. Data taken from the front page, the drawings and the claims of the original document.
Application filed with the U.S. Patent Office.
Patent US 3,216,423 granted.
4 sheets · 5 figures · 10 columns of description · 14 claims.
02 · Architecture
The whole apparatus is organised around the vertical shaft 14. A concrete floor slab 10 and a cast-iron base plate 12 carry the anti-friction bearing 13.
Channel irons 25 bolted onto sheave 20, which is fixed to the shaft, carry the I-beams 26 and the steel deck plate 28. The removable stretcher 24 is fastened on top, with the head over the centre of rotation.
Slab, base plate, bearing, motor, reducer, controller, brake and fence.
Shaft, sheave 20, beams, deck, ballast, stretcher, receiving net and governor.
Approximate scale. The patent gives no dimensions. Proportions are inferred from the drawings; labels use the document's reference numerals.
03 · Exploded view
The exploded view separates the sub-assemblies along the vertical shaft. Select one to highlight it and read its card.
Explanatory visualisation. The order of separation does not reflect a documented assembly procedure.
04 · Mechanism
A variable-speed vertical gear motor 15, regulated by controller 16, drives the shaft at a "closely controlled" speed through sheaves, belts and a speed reducer.
Beams 26 and everything they carry revolve horizontally around the shaft; the base, the motor and the fence stay fixed.
A platform rotates about a vertical axis with the patient's head near the centre and the body laid out radially. The text explains that the force increases with speed and with distance from the centre.
According to the patent, the rotational force was meant to add to the mother's own pushing in order to overcome the friction and constriction that oppose birth; an operator, instructed by the physician, increased the speed up to the planned value.
Normalised 0–1 scale. The control only changes the speed of the animation; it does not represent revolutions per minute or real accelerations. The patent does not state the direction of rotation: it is shown counter-clockwise by convention.
The patent includes a table relating speed and acceleration at three feet (≈ 0.9 m) from the centre: from 31.2 r.p.m. (1 g) to 82.3 r.p.m. (7 g). It is quoted as a document; the animation does not reproduce it.
05 · Stretcher and adjustments
Stretcher 24 is prepared away from the machine and fastened to the deck with bayonet extensions 35, bolts 38 and wing nuts 39. Each support slides along longitudinal slots and is locked with wing nuts.
Neutral volume. The "patient zone" is a translucent volume with no anatomy. The curvature of the girdle and the shapes of the boots and thigh holders are schematic.
06 · Counterbalance
On the other side of the shaft, on transverse beams 45, a ballast deck 46 carries "about ten" aluminium water tanks 47, each with a filling funnel 48, a drain faucet 49 and a sight glass 50.
According to the text, the water should exactly counterbalance the difference in weight on either side of the axis, and the amount is set by weighing the patient before the operation.
Conceptual diagram. The balance or stability of a real machine is neither calculated nor verified.
07 · Control and stopping
Conceptual dramatisation. It does not reproduce a test or demonstrate safety. The patent describes the electrical circuit as "conventional (not shown)"; the link between the rotating parts and the controller is not represented.
08 · Variants
Historical variants, not simultaneous functions. Figs. 4 and 5 only draw the stretcher support; the ballast and the rest of the assembly are not shown in those views.
09 · Documentation
The four original drawing sheets, extracted from the patent. Select one to enlarge it and compare it with the reconstruction.
10 · Critical reading
The patent describes a proposal. Separating what the document says from what it cannot prove is part of reading it well.
01 · The authors
The inventors state that they want to help the woman by "creating a gentle, evenly distributed, properly directed, precision-controlled force" that supplements her own efforts.
The rationale rests on claims about the muscular development of women from different peoples that the document does not support and that reflect ideas of its time.
02 · United States, 1963
More than four million births a year, few caesareans and still-high maternal and infant mortality: difficult births were an everyday problem.
Source: NCHS, 1965 natality and 1963 mortality reports. The rate of 36 per 100,000 is our own calculation.
03 · From patent to use
04 · Concerns
05 · Today
Sources: NCHS Health E-Stat 113 (Hoyert, March 2026); NCHS/HRSA 2023; NCHS FastStats 2024; Health, United States 2017; WHO, June 16, 2021.
This experience is a historical and mechanical reconstruction for educational purposes. The patent documents a proposed invention; it is not evidence of clinical efficacy, obstetric safety, manufacture or actual use. The animation does not represent a recommended medical procedure.
11 · Frequently asked questions
Documenttaken from the patent · Inferencereconstruction decision
DocumentIt is a United States patent titled "Apparatus for Facilitating the Birth of a Child by Centrifugal Force", filed on January 15, 1963 by George B. and Charlotte E. Blonsky and granted on November 9, 1965. It contains four drawing sheets with five figures, a technical description and fourteen claims.
DocumentA fixed base (slab 10, plate 12, bearing 13) supports vertical shaft 14. A motor 15, a reducer 17 and sheaves transmit rotation to sheave 20, which carries beams 26 and deck 28. On top sit the removable stretcher 24 with its supports, the water ballast 45–50, the receiving net 88–97 and the governor 105–111. A fence 115 with gates 116 surrounds the assembly.
InferenceDimensions, the shapes of some parts and the radius of the fence have been estimated from the drawings, which include no measurements.
DocumentShaft 14 is the geometric reference: everything bolted to sheave 20 turns with it. The stretcher is positioned so that the head lies at or near the centre of rotation, with the body oriented radially.
InferenceThe patent does not state the direction of rotation; the reconstruction shows it counter-clockwise by convention.
DocumentFig. 4 removes deck 28 and rests the stretcher on beams 26 and two standards 120: the foot end pivots on lugs 121 and the head end rests on rod 124, placed in one of holes 123. Fig. 5 hinges the head end in holes 125 and leaves the foot end free, rising as speed increases. The text justifies this by the combination of gravity and rotational force, and keeps the horizontal stretcher for high accelerations.
InferenceThe angles are reconstructed approximately. These are alternative variants, not functions of a single machine.
No. A patent documents a proposed invention and this animation is an explanatory reconstruction. Neither demonstrates clinical efficacy or safety. Later sources indicate that the apparatus was never manufactured or tested.
Nuestro insólito invento
Explore the relationship between design, engineering and inventive thinking through a three-dimensional reconstruction of a historical patent.
George B. Blonsky and Charlotte E. Blonsky. US Patent 3,216,423, "Apparatus for Facilitating the Birth of a Child by Centrifugal Force", granted on November 9, 1965.
Hover over or tap each reference to locate it on the model.
Highlighted relationships are only those that can be identified with confidence on the sheet. The reconstruction is not an original image.