THE ABERRATION OF SOUND AS ILLUSTRATED BY 
THE BERKELEY POWDER EXPLOSION 
By Robert LI. Chapman, 
United States Geological Surrey 
Dr Cl):irle.s A. Wliite* and Mr Arnold B. Johnson t have 
treated of the sounds given by fog-sirens. They have discovered 
areas close to the siren in which the sound is inaudible. In some 
cases this fact is accounted for by the intervention of an object, 
such as an island or mountain, but not infrequently there is no 
visil)le obstruction to the sound waves coming from the siren. 
It is my wish to ju’esent some facts that have come within my 
own observation and that show a direct relationship between 
sound waves and waves of motion generated b}' sharj) explosions. 
On Saturday, July 1), 1892, about 9.30 a. m., an explosion oc- 
curred at the giant-powder works at LVest Berkeley, California. 
The first explosion was in the “ mixing-room,” and about 1,000 
pounds of nitro-glycerine were discharged. About five minutes 
later the three magazines blew up, the final ex])losion being the 
heaviest. The total amount of powder and nitro-glycerine ex- 
ploded was about 250 tons. The shock of the last explosion was 
very severe, the column of smoke and flame rising to a height 
of at least 1,200 feet, and resembling a volcanic eruption. The 
damage in San Francisco, eight miles across the bay, was very 
great, ])late-glass windows being broken, doors forced, and sky- 
lights shattered. Tne shock seemed to be a little heavier in the 
low-lying portion of the city, although farther from the scene of 
the explosion, than in the hilly (piarter. It was distinctly felt by 
the engineer and passengers of a rapidly moving express train 
12 miles north of the works. A train only five miles distant was 
l)artially protected by hills, and no shock was noticed. At Napa, 
28 miles due north, the shock was distinctly noticeable. 
About one and one-half miles a little south of east of the works 
and at about 100 feet higher elevation is situated a large frame 
* Science, yo\. xxiii, pp. 59-62, The Relation of the Sounds of Fog Signals to other 
.Sounds. 
t Science, vol. xxiii, pp. 3-6, The Cruise of the Clover. 
See also The Modern Light-house Service, pp. “4-91, .4. B. Johnson, and Report upon 
Fog-signal Experiments (Report of the Light-house Board, 1891, Appendix No. V), 
pp. 289-304, W. R. Livermore. 
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