The short answer
A 250-foot steel tension wheel, with several figures still in dispute.
The 1893 Exposition wheel was a steel tension structure built like a bicycle wheel: 250 feet in diameter and about 264 feet to the top, thirty-six enclosed cars, a forged axle reported at shipment as 33 inches and 89,320 pounds (Rice and Weingardt give 32 inches and about 45 tons), steam-driven through endless chains at the rims.[1, p. 74][1, p. 86][1, p. 84][1, p. 107][1, p. 83][1, p. 126][1, p. 92][2, p. 477][2, pp. 475–480][3, pp. 615–616][3, p. 616][5, p. 8][6][7, p. 5][8][9, p. 25][10, p. 2][11, p. 576][11, pp. 274, 576–577][12, Item 8][13, pp. 19–21]Several of those figures still disagree in the sources. The table below keeps the range. How the Wheel was conceived and raised is on Building the Wheel; this page is what the finished machine was made of.
Mechanism
How the 1893 Ferris Wheel worked.
How did it carry its rim?
In tension, not compression. It was a steel tension wheel built like a bicycle wheel, with rods in tension rather than rigid spokes in compression. Rice gives the rods as 2-9/16 inches; Weingardt, and the 18 June Tribune, give 2½ inches.[1, p. 74][1, p. 107][2, p. 477][3, pp. 615–616][9, p. 25]The Tribune’s 18 June 1893 feature compared the structure to a bicycle wheel; Searles’s 1893 paper made the same likeness, with stated differences. The rod-diameter disagreement is contemporary, not a later error, and is not averaged here.
How was the axle made?
Forged at Bethlehem, Pennsylvania, from a 65-ton ingot, according to Bethlehem Iron’s own exhibit note in White & Igleheart’s 1893 fair book. The New-York Tribune, datelined Bethlehem on 20 March 1893, described the shipment as the largest piece of steel yet forged in the country: 45 feet 2 inches long, 33 inches in diameter, 89,320 pounds. Rice later gave 32 inches and about 45 tons; Searles, writing after watching the machine, gave 33 inches, 45½ feet, a 17-inch bore, and 93,000 pounds.[1, p. 74][1, p. 83][2, p. 477][3, p. 616][10, p. 2][11, p. 576]That “largest yet forged” line is a contemporary claim, not a comparison this site has independently checked against other forgings.
How was it driven and lit?
Driven by steam engines with a Westinghouse air brake, through endless chains at the rims; Barrett, the fair’s electrician, placed the boiler and dynamo plant 700 feet outside the grounds. Weingardt gives the engines as two 1,000-horsepower units, one in reserve.[1, p. 83][1, p. 107][13, pp. 19–21]Barrett recorded 1,540 lamps on the Wheel and 2,900 in all, wired by Western Electric, with collector rings at the hub. Press accounts of the 16 June preview round that to “more than 3,000.”[1, pp. 86–88][13, pp. 19–21, 'Lighting of the Ferris Wheel']
Calculations
Gronau’s numbers.
Rice’s 1901 account has William F. Gronau, a partner in Ferris’s firm, in charge of the detail drawings and strain sheets. Searles’s 1893 engineering paper, in discussion, cites Gronau for the Wheel’s weights and calculations. Gronau’s own 1893 paper has not been read independently; the encouragement anecdote remains Weingardt’s quotation of it.[1, pp. 74–75][2, pp. 475–476][3, pp. 619–621 (discussion)][4]Gronau’s 1893 paper has not been read independently here. The public wording does not treat Weingardt’s quotations as equivalent to opening Gronau himself.
The structure
What the sources give.
| Diameter and height | 250 feet in diameter and about 264 feet to the top — Engineering News said so in July 1893. Sources that say “250 feet tall” are usually quoting the diameter; a few contemporary pieces say 265.[1, p. 74][1, p. 86][1, p. 84][5, p. 8][6][7, p. 5][8] |
|---|---|
| Structure | A steel tension wheel built like a bicycle wheel, with rods in tension rather than rigid spokes in compression. Rice gives the rods as 2-9/16 inches; Weingardt, and the 18 June Tribune, give 2½ inches.[1, p. 74][1, p. 107][2, p. 477][3, pp. 615–616][9, p. 25] |
| Axle | A forged-steel axle about 45 feet long, reported at shipment as 33 inches in diameter and 89,320 pounds (Weingardt gives 32 inches and about 45 tons), described then as the largest piece of steel yet forged in the country.[1, p. 74][1, p. 83][2, p. 477][3, p. 616][10, p. 2][11, p. 576] |
| Cars | Thirty-six enclosed cars. Contemporary descriptions disagree on capacity: some give forty seats each, others sixty (forty seated plus standing), or 2,160–2,260 total.[1, p. 126][1, p. 92][2, pp. 475–480][5, p. 8][8][11, pp. 274, 576–577][12, Item 8] |
| Power | Driven by steam engines with a Westinghouse air brake, through endless chains at the rims; Barrett, the fair’s electrician, placed the boiler and dynamo plant 700 feet outside the grounds.[1, p. 83][1, p. 107][13, pp. 19–21] |
| Lighting | Barrett: 1,540 lamps on the Wheel and 2,900 in all. Press accounts of the 16 June preview round that to “more than 3,000.”[1, pp. 86–88][13, pp. 19–21, 'Lighting of the Ferris Wheel']Weingardt describes that preview, with some 3,000 lights on the structure, quoting the Pittsburgh Commercial Gazette.[1, pp. 86–88] |
| Ride | Fifty cents for two revolutions is independently in the 1893 guidebook and the 18 June Tribune. How long that took is in conflict: Rice has twenty minutes for the double trip; the Tribune expected one revolution every twenty minutes; Searles, after the season, gives nine minutes a revolution.[1, p. 92][1, p. 95][2, p. 479][3, p. 617][9, p. 25][12, Item 8][15] |
| Foundations | The Chicago Citizen of 12 August 1893 dates the start of foundation work to 8 January 1893 and describes thawing quicksand with live steam, matching Rice’s later account.[1, p. 83][2, pp. 475–480][7, p. 5]Rice’s 1901 account, matching that Citizen feature, describes thawing frozen quicksand with live steam to sink the foundations from January 1893.[1, p. 83][2, pp. 475–480][7, p. 5] |
| Fabrication | Rice describes fabrication spread across a dozen shops, with Ferris’s inspectors on the work; Engineering News recorded 2,200 tons put in shape at Detroit.[1, pp. 82–83][2, pp. 475–480][6] |
| Storm test | The Wheel came through a severe storm on 9 July 1893. Syndicated reports said it did not move “a hair’s breadth”; a letter in Engineering News, via Weingardt, gave about an inch and a half of sideways movement.[1, pp. 93–94][6][14, p. 1, syndicated] |
| Axle after 1906 | The axle’s fate is unresolved. One line of evidence, from Chicago House Wrecking Company records, says it was cut up in Chicago around 1919; St. Louis searches in 1943 and 2007 looked for a buried shaft and did not excavate.[1, p. 120][16, pp. 4–9][17, pp. 2–7][18][19, p. 8] |
FAQ
The 1893 machine, in question form.
How tall was the 1893 Ferris Wheel?
It was 250 feet in diameter and about 264 feet to the top — Engineering News said so in July 1893. Sources that say “250 feet tall” are usually quoting the diameter; a few contemporary pieces say 265.[1, p. 74][1, p. 86][1, p. 84][5, p. 8][6][7, p. 5][8]
How did the 1893 Ferris Wheel work?
As a steel tension wheel built like a bicycle wheel: the rim hung from the axle on rods in tension, not rigid spokes in compression. Steam engines with a Westinghouse air brake turned it through endless chains at the rims. Rice gives the rods as 2-9/16 inches; Weingardt, and the 18 June Tribune, give 2½ inches.[1, p. 74][1, p. 107][1, p. 83][2, p. 477][3, pp. 615–616][9, p. 25][13, pp. 19–21]
How big was the Ferris Wheel axle?
A forged-steel shaft about 45 feet long. The New-York Tribune’s Bethlehem shipment notice of 20 March 1893 gives 33 inches in diameter and 89,320 pounds. Rice’s 1901 memoir gives 32 inches and about 45 tons. Searles’s 1893 paper independently gives 33 inches, 45½ feet, a 17-inch bore, and 93,000 pounds. All three stay on the record.[1, p. 74][1, p. 83][2, p. 477][3, p. 616][10, p. 2][11, p. 576]
How many lights were on the 1893 Ferris Wheel?
John P. Barrett, the fair’s electrician, recorded 1,540 lamps on the Wheel and 2,900 in all. Press accounts of the 16 June preview round that to “more than 3,000.” Barrett’s count is the electrical record; the preview figure is a newspaper’s.[1, pp. 86–88][13, pp. 19–21, 'Lighting of the Ferris Wheel']
Where is the original Ferris Wheel axle?
Unresolved. One line of evidence, from Chicago House Wrecking Company records, says it was cut up in Chicago around 1919; St. Louis searches in 1943 and 2007 looked for a buried shaft and did not excavate.[1, p. 120][16, pp. 4–9][17, pp. 2–7][18][19, p. 8]