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Henry G.J. Moseley - Battle Death at Gallipoli of Promising Young Physicist

James Patton, BS
Military Historian, U.S. Army Veteran, and WW-I Feature Writer

Gallipoli Peninsula, June 1915: The invasion was stalled. An ambitious, complicated plan was devised, the execution of which would prove impossible.

Battle Map of the Anzac Breakout
Battle Map of the Anzac Breakout, 6-8 August 1915

The attack was set for August 6th. Diversions would be mounted at Lone Pine, the Nek and Krythia Vineyard. At dawn, troops would land at Suvla Bay six miles north of Anzac Cove and move across the peninsula to cut off the Ottoman defenses. Success depended on capturing the Sari Bair highlands, so another force would be secretly assembled near Anzac, and capture the peaks by noon. Problems arose immediately. The beach was too small, there was no moonlight, the terrain was rough, maps were poor or wrong, and there were no guides. Everything had to advance through winding defiles less than one yard wide. Even the highly-regarded Australians and Gurkhas couldn’t advance fast enough.

At dawn on the 7th no peak had been taken. New Zealanders captured Chunuk Bair that night. The Gurkhas took Hill Q on the 10th but were driven off by friendly fire; the Australians never made it to Hill 971. While men were dying on the highlands and in diversions, the Suvla Bay force had stopped; the commander waiting to land everyone. The enemy reinforced and the attack on the 9th was stopped cold. An ad hoc force was formed, called ‘Baldwin’s Brigade’ after Brig. A.H. Baldwin. On the 9th they tried to capture the ridge between Chunuk Bair and Hill Q, but stopped at the flat-topped hill directly below called ‘The Farm’.

At dawn on the 10th 30,000 Ottomans led by Col. Mustafa Kemal overwhelmed the defenders on Chunuk Bair and smashed into Baldwin’s hapless men, who had not constructed defensive positions. A Kiwi observer above likened the sight to a “human waterfall”. Baldwin’s command post was wiped out, including the signals officer, 2nd Lt. Henry Gwyn Jeffreys Moseley, the most promising English physicist of his generation.

2nd Lt. Harry Moseley RE
2nd Lt. Harry Moseley RE

Moseley, called ‘Harry’, was born into a wealthy, eccentric, scientific family in 1887. He attended Eton, then Trinity College, Oxford, where he graduated in 1910 with a Second.

Harry’s ambition was to work at Manchester under the Nobel Laureate Sir Ernest Rutherford. That Harry had a living courtesy of his grandfathers may have decided Rutherford’s choice, but he wouldn’t regret it.

Rutherford’s laboratory was bombarding ultra-thin sheets of gold foil with alpha particles, the positively charged particles found in the decay of radium. Mostly the alpha particles would pass through the gold foil, but occasionally one bounced back.

Thus, Rutherford had postulated his atomic theory: all of the positive charge and most of the mass of the atom were concentrated in a tiny central core with the electrons orbiting this ‘nucleus’, Thus, most of the atom was empty space.

Harry Moseley in His Lab
Harry Moseley in His Lab

Meanwhile Harry was studying Beta Rays, and had discovered the principle of the atomic battery, which would not be produced until the 1950’s. Delayed by equipment delivery, he decided to look at X-rays. It was known that X-rays could be ‘diffracted’ much like light can be broken into a spectrum of colors with different frequencies. Harry and Charles G. Darwin (grandson of the great biologist), found that the clarity of the spectra allowed atomic structure to become the subject of the experiment, rather than X-rays.

Harry found that each element has a unique X-ray diffraction spectrum – like a fingerprint - that can identify it. He also found a simple relationship between an element’s spectrum and its ‘atomic number.'

Harry postulated a theory (later called Moseley’s law) which proved what Niels Bohr had predicted – that the frequency of X-rays is proportional to the atomic charge. The elements could be ordered according to atomic number. Up to then, atomic number had just referred to the number of an element’s box in the Periodic Table. Harry’s work showed it was actually a measure of the positive charge on an atom’s nucleus. He published his famous step ladder, showing the increasing frequency of the x-rays from calcium to copper.

Moseley's First Step Chart
Moseley's First Step Chart

Moseley and Rutherford changed the Periodic Table. Its author, Dmitri Mendeleev, had relied on atomic weight in building the table, but they showed the table’s foundation is actually atomic number: Each element in the table has one more proton in its nucleus than the element before it.

By using his X-ray spectroscope, Harry could determine whether a sample was a new element or a compound of known elements. Harry also solved the Mendeleevian problem of the “rare earths,” certain elements whose properties were so similar that they had confounded chemists. And his most electrifying finding: exactly how many elements remained to be discovered – and where they would fall in the Periodic Table. Harry had set forth the basis for the modern Periodic Table, predicted the elements that would fill in the gaps and shown that x-rays could be a supreme analytical tool. Few achieve in a lifetime of research what he did in a career of just 40 months.

Harry was tragically unlucky in that he came of age in an era when war was considered an adventure rather than a catastrophe. Rutherford later wrote in a newspaper article: “It is a national tragedy that our military organization at the start was so inelastic as to be unable, with a few exceptions, to utilize the offers of services of our scientific men except as combatants in the firing line. Our regret for the untimely death of Moseley is all the more poignant because we recognize that his services would have been far more useful to his country in one of the numerous fields of scientific inquiry rendered necessary by the war than by the exposure to the chances of a Turkish bullet.”

All images are in the Public Domain. For more information see: Heilbron, J.L. “The Life and Letters of an English Physicist 1887-1915”, University of California Press, Berkeley and Los Angeles: 1974.

Last modified: Jul 26, 2018