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Decay doesn’t come about by itself. As Pasteur showed, it’s the work of germs, living things that get in from outside and multiply. What spreads infection is the germs, not decaying matter as such.

In my wards, 16 of 35 patients died after amputations before I began killing germs with carbolic acid, and 6 of 40 since. The air is the same as before; only the germs are gone.

Wounds fester for the same reason broth goes bad: germs get into them from outside. Kill the germs, on the wound, the instruments, and the surgeon’s hands, and wounds heal clean.

Broth boiled in a flask with a long, bent neck stays free of life, though air reaches it, because the germs carried by the air’s dust settle in the bend. Tip the flask so that the broth touches the bend, and it soon teems with microbes. They come from germs, not from the broth.

Microscopic life arises on its own in broths and infusions, from the decaying matter in them, whenever conditions allow.

Newton’s law isn’t wrong. Unseen matter inside Mercury’s orbit, a planet or a ring of small bodies, would explain the difference. That’s how the unseen Neptune explained the odd motion of Uranus.

Mercury’s perihelion moves about 38 arcseconds per century more than Newton’s law predicts from the pull of the known planets.

Where two water companies supply the same streets, houses drinking Thames water taken below London’s sewers lose more than eight times as many people to cholera as houses drinking water taken above them. Same streets, same air, different water.

The Broad Street outbreak’s deaths cluster around one pump, and those spared drank other water: the workhouse its own well, the brewery’s men their beer. Bad air would have spared no one in the same streets.

Cholera is caused by a poison that multiplies inside its victims, leaves them in their waste, and spreads when others swallow it, mostly in water fouled by sewage. “For the morbid matter of cholera having the property of reproducing its own kind, must necessarily have some sort of structure, most likely that of a cell.”

A long pendulum’s swing turns slowly clockwise, about 11 degrees an hour in Paris, though nothing pushes it sideways. The floor beneath it turns, with the spinning Earth. A motionless Earth can’t explain this.

Light travels more slowly through water than through air: measured with a spinning mirror, the light that went through water comes back later. Newton’s particles, pulled into the water, would travel faster there.

In October, the doctors examined a woman with a foul-smelling cancer of the womb, washed only with soap, and went on to twelve women in labor. Eleven of them died, though no corpse was involved.

Childbed fever kills mothers four times as often in the doctors’ clinic as in the midwives’ clinic next door, though both breathe the same air. Since the doctors began washing their hands in chlorine after dissecting corpses, deaths have fallen from 18 in a hundred births to 2. The cause comes on the doctors’ hands, not from the air both clinics share.

Childbed fever comes from particles of corpses, which doctors and students carry on their hands from the dissecting room to the mothers they examine. Wash them off in chlorinated lime, and the fever goes.

Diseases like cholera and fevers come from miasma: bad air given off by rotting filth, sewage, and swamps. Clean away the filth and its smell, and the disease goes with it.

The parallax is there, only tiny. Over the year, 61 Cygni moves back and forth by 0.31 seconds of arc either way against two fainter stars beside it, just as it should if the Earth circles the Sun. The stars are simply that far away: 61 Cygni is about 660,000 times farther from us than the Sun.

I put a small round disk in a narrow beam of light, and the bright spot is there, at the center of its shadow, just as Fresnel’s theory says.

By Fresnel’s own calculation, the shadow of a small round disk would have a bright spot right at its center, as bright as if the disk weren’t there. That’s absurd.

Light does bend into shadows, only very slightly, because its waves are so short. That makes the fine fringes along the edge of a shadow, and my calculation of the waves predicts exactly where they fall.

Light added to light can make darkness. Hold a thin card in a narrow beam of light, and bright and dark stripes appear in its shadow; block the light passing one side of it, and they vanish. Waves can cancel each other out. Streams of particles can’t.

Gamma Draconis, and the other stars I’ve measured, shift back and forth over the year by about 20 seconds of arc, always toward the direction the Earth is moving in at the time. Light takes time to arrive, and the Earth’s motion slants the direction it seems to come from. A motionless Earth can’t produce this.

A wave would bend around an obstacle and spread into its shadow, as sound bends around a corner. But light casts sharp shadows.