The Anthaeum was a truly massive hemispherical glass "space-age"-looking dome with a cast iron frame constructed in Hove in 1832-1833 as a giant greenhouse and recreation space, a loose pre-Victorian forerunner of the giant geodesic domes later created by Buckminster Fuller in the Twentieth Century.
Planned by Henry Phillips and designed by architect Amon Henry Wilds, the ultra-modern dome was on track to be the largest dome structure in the world, and a major landmark in the region, visible for miles around. If all had gone to plan, the futuristic high-tech dome would have been one of the most notable architectural structures on the planet. The dome was planned to be presented to the public on Saturday 31st August 1833.
Don't sack the technical experts
Unfortunately, the foundry commissioned to cast the dome's ribs was also the contractor tasked with building the dome ... which sounded reasonable, except that the architects and engineers weren't part of the contractor's management structure, and had no formal input into what happened next. What happened next was that the contractor, Henry English, fell behind schedule, decided to change the design, fell out with the engineer (who was thrown off the site), all the outside experts who'd been involved with the design realised that things were going pear-shaped and excused themselves from the ongoing project, after which English proceeded to do a "cowboy builder" job on the rest of the construction, changing key elements of the design to make them easier to cast, or quicker to build, without any independent engineering certification.
After the frame was finished, on Thursday 29th August 1833, just two days before the dome was due to be unveiled to the public, a concerned Phillips tried to get an outside engineer's opinion as to whether it was really safe to remove the scaffolding. The next day, Friday 30th August (the day before opening), English decided to go ahead take down the scaffolding framework, and with the job completed most of the workmen left the site that afternoon/evening. At around 7pm the struts started to crack, the centre of the dome fell in, and much of the remainder of the structure then collapsed during the night.
Things could have been much, much worse – The fact the that bodged structure was unable to support itself even for a few hours averted major loss of life. In the event, nobody was (physically) hurt: if the structure had managed to survive through the night and into the morning before the first strut cracked, the five hundred tons of ironwork might have collapsed during the official launch, onto an large assembled invited crowd of press and public, with terrible results – it could have been the most disastrous unveiling in public relations history. "Anthaeum" would have become a household word, like "Titanic".
A horrified, dejected and demoralised Phillips went blind from the shock of seeing his beloved project turn into a crater of wreckage the very day before he was supposed to proudly present it to the world, and the megastructure's ruins remained in place for over a decade, becoming a tourist attraction in their own right (much like the skeletal framework of the West Pier, today).
After the Anthaeum collapse, the frantic rate of housing development across Brighton and Hove seemed to slow a little. It's possible that the developer community might have slightly lost their nerve at the thought that their eagerness to go "full steam ahead" had almost been responsible for their inviting some of the most important, most wealthy, and most influential members of Brighton society to stand inside the dome at "ground zero" to be crushed to death as the roof fell in, with the press in attendance.
1872 RIBA post-mortem:
FALL OF THE IRON DOME OF THE ANTHAEUM AT BRIGHTON
THE iron dome of the Anthaeum or Oriental Garden, situated at the western extremity of Brighton, fell in at a quarter to seven o'clock on the evening of Friday, 30th August, 1833. The dome was composed of wrought and cast-iron ribs resting on a brick foundation, and weighed between 400 and 500 tons. The erection of such a vast dome in those days was considered an important event, and in iron certainly without a parallel. It exceeded in diameter that of St. Peter's, at Rome, by 36 feet; the width of the dome at bottom being 164 feet, and the height from the ground to the top of the ring exactly 64 feet; with the cupola it would have been 80 feet or more in height outside. The dome was not, like St Peter's, placed on a height; but it rose at once out of the ground.
It was commenced in July 1832 from a design by Mr. Henry Phillips, the well known botanist of the town, after having been submitted to some of the first engineers and architects of the day. Mr. Henry English of the Griffin Foundry, Clerkenwell, contracted to erect the building under an engineer and architect of his own appointing. On the 29th July, 1832, Mr. Henry Wilds, as architect, laid out the ground, and the brick foundations into which the iron principals were built, were proceeded with. The scaffolding was erected in circles five in number, each ring exceeding the other in height. Principals after principals were bolted into position under the inspection of Mr. Peter Hollis, the engineer; but a misunderstanding arising between the architect and the engineer, the former was dismissed. The engineer then ceased to give his personal attendance at the works; delays ensued, which were at last accounted for by the embarrassment of the contractor's affairs. Still the works proceeded; the iron work of the dome was all but completed; and several weeks before the accident the scaffolding had been struck. Some doubts arising as to its security, a second engineer was called in, who proposed some additional iron purlins. The scaffolding was again raised, and struck, being entirely removed by seven o'clock on Thursday evening. The writer of the article in the Brighton Guardian newspaper (of Sept 4th, 1833, from which these notes are obtained) had remarked the heavy appearance of the top and a peculiar twist of some of the ribs which had acquired a considerable bend. Mr. Phillips was occupied during Friday under the very centre of the dome, marking out the formation of an aquarium. A little before seven o'clock, a gardener was alarmed by a loud cracking noise, when in a few seconds the whole top part of the dome fell in, and during the night many of the principals which had remained standing came down with a crash.
Of the cause of the dome falling, there were various opinions; but the most general one was that the dome was much too flat on the top. Mr. Phillips' design showed a half-circle, with a support in the shape of a pagoda in the centre. Mr. Hollis dispensed with this and made the dome much flatter. It was also intended that the large ring upon which the ribs rested at the top should have been 27 feet in diameter; but that size being found inconveniently large to cast, it was reduced to a diameter of 7 feet. and another row of principals added; so that the flatness of the dome was by that means increased and its security diminished, for the ribs lost their strength before arriving at the centre, and instead of pressing towards the ring, their own weight gave them an inclination to fall, and the ring intended for their support really acted as a lever to pull them down. The ring and two rows of the principals fell in one mass to the ground, indeed it appears that the top fell right through the dome, and the iron gave way as nearly as possible at the point where the flatness commenced. It is also thought that the ribs acquired a twist, and so the whole building screwed round (as it were) together and got out of its proper position. The brick walls and foundations into which the bolting of the ribs were built stood as firmly as ever. It was hoped at the time that the Anthaeum might have been reconstructed, but this has not been done.
If any member possesses a record of this building it would be desirable that a copy of it should be deposited at the Institute
— , Royal Institute of British Architects, , Fall of the Iron Dome of the Anthaeum at Brighton, , Transactions, , 1872