Here is a concise summary of the provided text:
**Title:** Unacknowledged Technologies of the Recent Past
**Main Claim:** The text suggests that there were advanced technologies in the 18th and 19th centuries that have since been lost or suppressed, contradicting the conventional narrative of linear technological progress.
**Key Examples:**
1. **Transportation:**
* Single-wheeled vehicles (e.g., unicycles, monowheel cars) that reached high speeds.
* Underground pneumatic transport systems.
2. **Construction:**
* High-quality, long-lasting brickwork in ancient buildings and tunnels.
* Impressive medieval structures (e.g., dams, fortresses) that surpass modern construction standards.
3. **Energy:**
* Speculation that domed buildings in 19th-century industrial exhibitions were used to harness electricity from the environment (ether).
**Implications:**
* The existence of these technologies challenges the traditional view of technological progress.
* The text hints at the possibility of intentional suppression or loss of knowledge.
* Readers are encouraged to question the narrative and share their thoughts.
Here are the extracted key facts, numbered and in short sentences, without opinions:
**Transportation**
1. In the late 18th and early 19th centuries, single-wheeled transportation mechanisms existed.
2. Examples of single-wheeled transport included horse-drawn carriages, bicycles, and motorcycles.
3. Some single-wheeled motorcycles could reach speeds of up to 150 km/h.
4. In 1970, Leningrad engineer Eduard Melnikov built a unicycle, but was forbidden to use it on roads.
**Underground Tunnels**
5. Many large cities have kilometer-long tunnels, similar in size to those depicted in movies like "Kingsman".
6. These tunnels were often attributed to medieval sewer systems.
7. The construction of these tunnels required significant investment and high-quality masonry.
**Construction and Architecture**
8. The quality of bricks used in modern construction is often inferior to those used in past centuries.
9. Ancient reservoirs, like one near Alicante, Spain, were built with advanced masonry (first stone laid in 1589, completed in 1594).
10. The dam's height is 41 meters, width is 33 meters, and its sluice system still functions today (over 400 years later).
11. The Sayano-Shushenskaya hydroelectric station (built in the Soviet era) did not last 50 years without major repairs.
12. Medieval buildings, like those in Saratov's dungeons, showcase superior masonry quality compared to modern bricks.
**Historical Structures and Dates**
13. A Swedish fortress, pillow, artificial island (surrounded by man-made canals) was constructed starting from 1626.
14. The fortress's brickwork, over 2 meters thick, withstood centuries, including two World Wars.
15. A bridge in Kiev, dated 1855, was built with high-quality steel, a year before the discovery of steel production secrets (according to academic sources).
**Industrial Exhibitions and Electricity**
16. Industrial exhibitions in the 19th century featured abundant architectural forms, potentially tied to electricity production.
17. Domed buildings at these exhibitions might have been sources for obtaining electricity from the surrounding space.
18. An All-Russian industrial exhibition in Nizhny Novgorod (early 1900s) featured advanced construction equipment, later destroyed.
19. A moving electric sidewalk (3.5 km long, with 9 stations) was showcased in Chicago (1893) and other exhibitions.