Grandinifughi
Last week I ran across these strange devices while looking for something else, as usual.



On further reading, it turns out that hail cannons were a big business for about 20 years. French and Italian farmers were convinced that the cannons made a difference. Like cloud seeding, they didn't halt the weather every time, but they dissipated hail often enough to save massive amounts of money and trouble. Unlike cloud seeding, there was no downside. Seeding is a zero-sum procedure, depriving one location of rain to favor another location. Deicing the hail doesn't move the precip, it just avoids the damage.

Major agricultural implement companies made hail cannons along with plows and seeders and cream separators. Genuine scientific conferences were held annually, showing off the latest experiments and inventions.

The French called them canons contre grèle or grelifuges, and the Italians called them Grandinifughi. A word you can chew on!

Here's part of a wonderfully lyrical account from a 1901 cultural magazine (p 662 of the PDF):

The terror of hail is as old as Adam's first planting season, and the hysterical efforts of man to do away with it date from that same springtime. It is just another phase of man's striving to climb back into Eden, where it does not hail. So he rang bells and made other noises, at first in religious appeal, and then with a vague notion of turning the storm by deafening detonations. Neither is the more scientific idea of shooting against clouds a new one. In 1760 the Chevalier de Jancourt, a physicist, noted that it never hailed on besieged towns, and urged wise men to get to work against what he called the most costly form of divine wrath. But the wise men were not wise enough, and the peasants rang their bells as before, and then declared that it would have hailed harder if they had not rung them.

The author visited actual farms and watched the Grelifuges in action. He talked to the farmers and grape-growers and scientists. Conclusion:

Cannons have been fired against hailstorms, and hail did not fall. You might say that hail would not have fallen anyhow. But it did fall anyhow - that is, all around except on the spot covered by cannon.

Again there remains the other possible coincidence: namely, that the hail had no designs against that particular exempted spot in the first place. But there is still an answering fact; for when the shooting ceased, the rain changed to hail, and when the shooting recommenced the hail as quickly changed back to rain. This is not an isolated instance, but the general case. .......

A veteran artilleur who had lost a leg in the service demonstrated how simply and safely this particular gun can be handled. He first produced one of the empty cartridges. This was of specially forged steel, about eight inches long. He adjusted a percussion cap, rammed in eighty grammes of mining powder, and ended with a wad of soft wood...

The artilleryman advised us to watch for the whirlwind-ring, and then he pulled the string. The explosion sounded like the heavy boom of rock-blasting. You knew vaguely that the tripod was hidden in smoke, and that a white cloud had puffed from the mouth of the funnel. Then, as though growing out of the shock of the explosion, there came the sound of a long, shrill whistling. It was like the fierce metallic singing of some monster tuning-fork, mounting to a more angry pitch as it hurled higher in air. There, away up in the sky, was a gauzy ring as of smoke, still ascending and still buzzing on that shrill crescendo note. The ring was outlined against the deep blue like a soft, silky wreath, in the rays of the sun it was brilliant and changing, and then again shaded. One second later, and it had vanished in space. That, briefly, is the tore, or whirlwind-ring, which bursts from the cannon.

And what happened after the vortex penetrated the cloud?

But even as the spectator on the hill was losing hope for the much-vaunted cannon, he looked up again. There was a disturbance going on in the darkest cloud, just over the vineyards. It looked like billows of rolling, tossing smoke up there. Then all at once the cloud opened, and through the rift was the glorious gold of the afternoon sun. At last, here was a breach in the enemy's flank. A gunner below shouted involuntarily, and all of them worked faster and faster yet. Each cannon was counting two, three, shots to the minute. Other breaks showed in the clouds. There was a moment of wavering, and then panic. The dark-browed invader broke and fled. He scattered towards the hills, and in his retreat he sent down a discouraged volley of raindrops.

Or in more prosaic form, the cannons broke the updrafts that encouraged hail, and left a heavy rain.

Here's my attempt to capture the scene.



Polistra is at the controls of CANNONE FORMIDABILE, a full-fledged artillery piece with azimuth and altitude adjustments:



Happystar is supervising a cannon built into its own cozy shed, with a separate inner room where the tireur could sit and wait for the storm while sipping the products of the vineyard he was protecting.



An automatic acetylene cannon is in the background, developed by Maghiora and Blanchi.



Did the cannons make sense? We know from wind-tunnel studies of streamlining that a vortex breaks up smooth airflow. The purpose of streamlining is twofold: First avoid flat surfaces directly pushing the air; second, avoid vortices. You want the air to split smoothly around the car or plane, and rejoin smoothly afterward.

The end of the Grandinifughi era isn't clear. Did the farmers decide that the Grandinifughi weren't worth the effort? Or did insurance companies make damage more profitable than prevention? Flood insurance works that way.

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Happy ending! Grelifuges are STILL USED in France and Italy, and STILL MADE in Spain, and they look about the same as the 1902 versions! The new cannons use acetylene, continuing the tech invented by Maghiora and Blanchi. Video of a modern grelifuge. Live action with a visible and audible whirlwind-ring at 4:14. The old description wasn't lyrical, it was accurate!


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Etymological footnote: The French and Italian words for hail are opposite. Grèle comes from Latin gracilis, and means slim or small when used as an adjective. Grandini comes from a root meaning 'coarse-grained', thus by extension grinding and grain and grand and things that grind, including hail. My initial impression of 'chewiness' was spot on.

Labels: 1901, Asked and partly answered, Happy Ending, Morsenet of Things

  ¶ 5:11 PM