AS A VEHICLE OF SOUND. 
22 ! 
it would be still more serviceable. At 7f miles the sound of the syren practically 
vanished. 
Halted at 8 miles and listened : the syren was faintly heard, and after a little time 
seemed to rise in power. This has been an almost daily experience. After the stoppage 
of the paddles the ear appears to require a little time to recover its entire sensitiveness. 
It may be questioned whether the change of intensity in passing from 7 to 7f miles 
was due to the increase of distance alone. It was probably due to the passage of an 
invisible acoustic cloud ; as we waited, not only did the sound of the syren rise in power, 
but that of the horns became distinctly audible. 
At 12.0 the gun was fired, and 46" afterwards a faint but perfectly distinct report was 
heard. 
Steamed on, the air being very light and the water very smooth. A thin haze over- 
spread the whole surface of the sea, the horizon not being so sharp nor the coast of 
France so visible as they were yesterday. At 9 miles we stopped and listened. Both 
the French and English coasts were very dim with haze ; the sun, however, was shining. 
From the bridge of the 4 Galatea’ occasional tones of the syren of the faintest character 
were heard ; from the stern of the vessel the syren-sounds were also heard, but they 
were exceedingly faint. Once or twice the murmur of the horns was feebly heard ; but 
on one occasion they rose to positive distinctness, this being entirely due to the varying 
state of the air. 
At 12.30 Ave saw the puff of the gun, and 50" afterwards, the distance being 9‘2 miles, 
heard a faint but distinct report : the gun-sound here was better than that of the syren. 
Stopped at 10 miles. From the stern of the vessel both syren and horns were heard 
as plainly as at 9 miles ; if any thing, more plainly. 
At 11 miles both syren and horns were faintly heard, a little more faintly than on the 
last occasion, but still quite distinct. Up to this point the sea had been of glassy smooth- 
ness ; it now became very slightly ruffled. The horns on this day and at this distance 
seemed at times equal to the syren ; at times, however, inferior to it. 
At 1 p.m. a gun was fired. The report was fair, and much beyond the intensity of 
the syren ; the day had evidently become favourable to the transmission of the longer 
sonorous waves. 
Stopped at 15 miles. From the stern of the vessel Mr. Douglass and myself heard 
distinctly the very faint report of the 1.30 gun. A little afterwards guns fired at Dover 
were distinctly heard. We learned subsequently that they had been employed in target 
practice. We waited and listened for some time at 15 miles distance : both horns and 
syren were heard occasionally. 
A little after 2 p.m. we heard a dull report, exactly answering to our time of firing ; 
but half a minute afterwards we heard a second similar report from one of the guns at 
DoA'er. Distance about 16^ miles, near Quenocs buoy, in front of Cape Blanc Nez. 
Besides the gun, nothing was here audible. This was the maximum acoustic range 
attained during this inquiry. 
