The cause of a silent battle.1
Reference has been made to the supposed effect of the wind in preventing, as in the case of the heavy cannonading between the Merrimac
, the transference of sound-waves a distance of not over three and one-half miles over water; and at another time, during the bombardments of the Confederate
works at Port Royal
, a distance of not more than two miles. “The day was pleasant,” says the writer, “and the wind did not appear unusually strong.
” Yet “people living in St. Augustine, Florida
, told me afterward that the Port Royal
cannonade was heard at that place, 150 miles from the fight.”
It occurs to me that the effect of the wind is greatly exaggerated in these instances.
How an ordinary breeze could “carry all sounds of the conflict away from people standing within plain sight of it” and yet carry the same sound 150 miles in the opposite direction, is rather too strongly opposed to scientific fact to remain on record undisputed.
In all of these cases, is it not probable that the varying density of the air had much more to do with this strange acoustic opacity than the wind?
These statements call to mind the prevalent belief that fog, snow, hail, and rain, indeed, any conditions of the atmosphere that render it optically opaque, render it also acoustically opaque; which, up to the time of Mr. Tyndall
's experiments in the English Channel
, off Dover
, had scarcely been questioned.
His tests made in 1873-74 proved conclusively, as is now well known, that on clear days the air may be composed of differently heated masses, saturated in different degrees with aqueous vapors, which produce exactly the deadening effects described above.
I submit as a case in point a similar effect, and its explanation as furnished by Mr. R. G. H. Kean
to Professor Tyndall
, and considered by the latter of sufficient value to find a place in his published works:
On the afternoon of June 27th, 1862, I rode, in company with General G. W. Randolph, then Secretary of War of the Confederate States, to Price's house, about nine miles from Richmond.
The evening before General Lee had begun his attack on McClellan's army, by crossing the Chickahominy about four miles above Price's, and driving in McClellan's right wing.
The battle of Gaines's Mill was fought the afternoon to which I refer.
The valley of the Chickahominy is about one and a half miles wide from hill-top to hill-top.
Price's is on one hill-top, that nearest to Richmond; Gaines's farm, just opposite, is on the other, reaching back in a plateau to Cold Harbor.
Looking across the valley, I saw a good deal of the battle, Lee's right resting in the valley, the Federal left wing the same.
My line of vision was nearly in the line of the lines of battle.
I saw the advance of the Confederates, their repulse two or three times, and in the gray of the evening the final retreat of the Federal forces.
I distinctly saw the musket-fire of both lines, the smoke, individual discharges, the flash of the guns.
I saw batteries of artillery on both sides come into action and fire rapidly.
Several field-batteries on each side were plainly in sight.
Many more were hid by the timber which bounded the range of vision.
Yet looking for nearly two hours, from about 5 to 7 P. M. on a midsummer afternoon, at a battle in which at least 50,000 men were actually engaged, and doubt-less at least 100 pieces of field-artillery, through an atmosphere optically as limpid as possible, not a single sound of the battle was audible to General Randolph and myself.
I remarked it to him at the time as astonishing.
Between me and the battle was the deep, broad valley of the Chickahominy, partly a swamp shaded from the declining sun by the hills and forest in the west (my side). Part of the valley on each side of the swamp was cleared: some in cultivation, some not. Here were conditions capable of providing several belts of air, varying in the amount of watery vapor (and probably in temperature), arranged like laminae at right angles to the acoustic waves as they came from the battle-field to me.”3