Aberdeen chronograph

The Aberdeen chronograph was the first portable instrument for measuring ordnance muzzle velocity and striking power. It was invented in 1918 by Alfred Lee Loomis at the U.S. Army's Aberdeen Proving Ground. The method prevalent at the time was the Boulenge chronograph, which relied on the projectile breaking two wire screens and measuring the time between circuit-breaking. Loomis' invention improved on the Boulenge chronograph in simplicity, accuracy, reliability, ease of operation, and ease of mass production. Loomis' chronograph

... consisted of an aluminum disk spooled with ticker tape, which a small motor kept revolving at a constant speed. Instead of breaking a circuit on contact, the shell created an electrical impulse when it hit each screen, causing a spark to burn a small hole in the tape. Shell velocity could easily be calculated by measuring the distance between the spark holes.

The Aberdeen chronograph was issued a patent, with Loomis named first, and it quickly became standard ordnance instrumentation for the U.S. Army and Navy. Loomis went on to a very successful career in investment banking. However, the experience of developing the instrument brought Loomis into contact with a number of scientists and engineers with whom he maintained a connection for decades afterward. Aside from the relative rarity of an invention improving so significantly in so many ways upon a previous method (or perhaps precisely because it did), the Aberdeen chronograph seemed to have stoked Loomis' interest in science and invention, and thus was a key stepping stone in a career that brought many scientists under his philanthropic sponsorship later, which in turn led to key developments in radio-based navigation such as LORAN and radar. As one biographer remarked

... Loomis was never at peace with himself about spending his days preoccupied with money. He had come to believe that science was a higher calling and was troubled by the growing sense that much of his work was self-serving and profited men he neither liked nor admired. He could not forget the pride in achievement he felt at Aberdeen, culminating in the award of the chronograph patent ....

Luis Alvarez, himself a sometime inventor, admitted to not being fully appreciative of the Aberdeen Chronograph, but seemed to understand its impact on Alfred Loomis. Alvarez wrote in his memoirs that

Alfred Loomis may well be remembered as the last of the great amateurs of science. He had distinguished careers as a lawyer, as an Army officer, and as an investment banker before he turned his full energies to the pursuit of scientific knowledge, first in the field of physics, and later as a biologist. By any measure that can be employed, he was one of the most influential physical scientists of this century.

Alvarez remarked further that the chronograph was a significant invention by any measure.

At Aberdeen, he was thrown into daily contact with some of the best physicists and astronomers of this country, and he and they benefited from each other's talents. In those days, before photoelectric cells and radar sets came to the aid of exterior ballisticians, there was no convenient way to measure the velocity of shells fired from large guns. Alfred invented the Aberdeen Chronograph, which satisfied that need for many years after its invention. It is hard for someone like me, who came into a scene long after an ingenious device had been invented, and later supplanted, to appreciate what made that device so special. But the fact that Alfred singled out the Aberdeen Chronograph for mention in his entries in Who's Who and American Men and Women of Science, and mentioned it on a number of occasions in conversations with me, makes me believe that it must have been a remarkably successful and important invention.

External links

• Eugene Lee Slover's Naval Pages, Naval Ordnance 1937, Ch. XV: The Naval Proving Ground, contains a more detailed description of operation.