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To determine the wind and temperature corrections,
the BEF set up “wind sections” behind the front lines. A “pound or so of explosive was set off at intervals of a few
hours and the sound was recorded by a series of micro- phones” whose positions were accurately known, thus determining the effects of temperature and wind.
Wind also produced turbulence as it flowed over the micro- phone. This cooled the wire and was a source of noise, referred to as wind noise. The early sound rangers experi- mented with several methods to mitigate this. Wrapping the microphone in camouflage netting helped, as did putting a thick hedge around the microphone (Mitchell, 2012).
A secondary use of SR was to register or correct the fire of friendly artillery since the microphones were able to detect the bursts of shells fired on enemy targets. The SR record of friendly fire was compared with the SR record of the enemy gun. The SR section would be able report to the artillery that the shell had fallen so many meters short or to the side of the target. Corrections would be made until a direct hit was achieved. This practice was independent of wind and weather because the record from the gun and the shell bursts were made under the same conditions.
The Battle of Arras near Vimy Ridge in April 1917 pro- vided a specific example of the effectiveness of flash ranging and SR. Before the attack, three SR sections coordinated their results to locate a giant German gun 11 miles behind the front lines (Van der Kloot, 2005). Other locations provided by flash ranging and SR enabled Canadian artillery to take out 83 German batteries. Having dealt with the enemy artillery, Canadian troops attacked under a creeping barrage, shells fired by the artillery approximately 200 yards in front of the advanc- ing infantry, designed to keep German machine gunners in their trenches. Other tactical adjustments that had been learned over three years of warfare had been made. The Canadians took and secured the ridge at the cost of 10,000 men. This compares with the 200,000 troops the French had lost in three previous attempts between 1914 and 1916. The Germans lost similar numbers defending it (Finan and Hurley, 1997; Meyer, 2006).
Concluding Remarks
The armistice went into effect on November 11, 1918, at 11:00 a.m. A sound recording was produced from a film strip recorded from 10:59 to 11:01 a.m. on the American Front near the River Moselle at the end of the war (see
The cannons fired right up to the time of the armistice, and it was so quiet immediately after that one could hear birds singing. The Imperial War Museum website has other information of interest (see
SR was not the only application of acoustics to warfare in WWI. Namorato (2000) describes the efforts at using acoustics to detect and track aircraft and to detect tun- neling. There were also advances in underwater acoustics that was used to detect and track German submarines. A previous article by Muir and Bradley (2016) in Acous- tics Today also describes the efforts in underwater acoustics. Incidentally, William Henry Bragg, William Lawrence Bragg’s father, contributed to this effort (Van der Kloot, 2005).
I thank David Swanson for introducing me to this topic and sharing references. I also thank the staff of the library at the US Army Engineer Research and Development Center, recognized as the 2017 Fedlink Large Federal Library of the Year, who were very helpful in finding many of the references used in this article. In addition, I acknowledge the contributions and sacrifices made by the flash and sound rangers in World War I. Permission to publish was granted by the Director, Geotechnical and Structures Laboratory, US Army Engineer Research and Development Center.
Bragg, L., Dowson, A. H., and Hemming, H. H. (1971). Artillery Survey in the First World War. Field Artillery Survey, London.
Finan, J. S., and Hurley, W. J. (1997). McNaughton and Canadian operational research at Vimy. Journal of the Operational Research Society 48, 10-14.
Hinman, J. R. (1919). Ranging in France with Flash and Sound. Dunham Printing Co., Portland, OR.
Kevles, D. J. (1969). Flash and sound in the AEF: The history of a technical service. Military Affairs 33, 374-384.
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