Cyrina

That water clarity is an engineering decision, and the math behind it is wilder than the video. Roman aqueducts ran on gravity alone. No pumps, no pressure systems. Engineers carved channels with a gradient so shallow it borders on absurd. The Pont du Gard in southern France drops 2.5 centimeters over 275 meters. That's roughly the thickness of a coin over the length of three football fields. They surveyed that accuracy with plumb lines and wooden leveling instruments. The clarity you're seeing is a direct product of flow velocity. Too steep and the water erodes the channel walls, picks up sediment, turns brown. Too flat and it stagnates. Roman engineers targeted a slope of about 20 centimeters per kilometer, which kept the water moving fast enough to stay fresh but slow enough to stay clear. Before the water reached the city, it passed through multi-chamber settling tanks where velocity dropped near zero. Suspended particles sank. Clean water flowed out the top into the next chamber. Repeat three or four times. Pliny specified the minimum slope in writing. Vitruvius published the exact mortar ratio for hydraulic cement: one part lime to two parts volcanic ash for underwater work. The pozzolana from Pozzuoli reacted with water to form a calcium-aluminum-silicate compound that actually gets stronger the longer it sits submerged. Modern concrete degrades in water. Roman concrete bonds with it. Scale the whole system and it gets harder to process. Eleven aqueducts fed Rome at its peak. Combined output: roughly 1 million cubic meters of water per day. That works out to about 250 gallons per person for a city of one million. Modern New York delivers about 125 gallons per person per day. Ancient Rome had access to double the per capita water supply of the largest city in the United States, running entirely on slope and stone. The Trevi Fountain in Rome is still fed by one of them. Two thousand years, same source, same gravity, same water.

Le Gouvernement simplifie et libéralise la prime carburant en la passant de 300 à 600€ ! Toutes les entreprises pourront aider leurs salariés face à la hausse des carburants. Cette prime est totalement défiscalisée et désocialisée, sans condition. Tous les salariés qui viennent travailler en voiture pourront la toucher.

Ten notable facts from India’s new SRS Statistical Report 2024 published two days ago: 1) India’s total fertility rate (TFR) has dropped to 1.88 (rounded up to 1.9 in the figures) in 2024 from 1.92 in 2023. 2) This drop is roughly the historical speed of the last few decades. India’s TFR was 4.3 in 1985 and it has been falling around 0.06 per year since then. 3) For those who think “smartphones are the reason for the fall of TFR,” there is not much change in India’s TFR after their introduction. Of course, this might only apply to India. 4) India’s sex ratio at birth continues moving toward natural levels. It has grown from 907 girls per 1000 boys in 2018-2020 to 918 in 2022-2024. Without sex selection (e.g., selective abortions), it should be around 952. 5) Nonetheless, this bias still means that India’s replacement rate is around 2.15, not 2.1 as in other advanced economies. 6) Hence, India is already 0.27 children below the replacement rate and the gap continues growing. 7) However, this figure hides large regional differences. Kerala is at 1.3, well below the U.S. and approaching Italian and Spanish levels (Delhi is even lower, at 1.2, but it is a peculiar case), while Bihar remains at 2.9. 8) In terms of the rural/urban divide, rural India is at 2.1 and urban India at 1.5. 9) From everything I can see, India’s TFR will continue to fall, and it should reach 1.57 (the current level of the U.S.) around 2031 unless something significant changes. 10) Having said that, India’s data has a non-trivial margin of error, and a new Census might change our reading of the situation. In summary, India is following the same path as everyone else. No Indian fertility Sonderweg!

This is alarming. Why do you think girls are so pessimistic today about marriage and motherhood? Look at the drop.