APPENDIX I.
THE SILVER SPRING.
The geological formation of Florida gives rise to springs and fountains of such magnitude and beauty, that they deserve to be ranked with the great freshwater lakes, the falls of Niagara, and the Mississippi river, as grand hydrographical features of the North American continent. The most remarkable are the Wakulla, twelve miles from Tallahassie, of great depth and an icy coldness, which is the best known, and has been described by the competent pen of Castlenau and others, the Silver Spring and the Manatee Spring. The latter is on the left bank of the Suwannee, forty-five miles from its mouth, and is so named from having been a favorite haunt of the sea-cow, (Trichechus Manatus,) whose bones, discolored by the sulphuret of iron held in solution by the water, are still found there.
The Silver Spring, in some respects the most remarkable of the three, is in the centre of Marion county, ten miles from the Ocklewaha, into which its stream flows, and six miles from Ocala, the county seat. In December, 1856, I had an opportunity to examine it with the aid of proper instruments, which I did with much care. It has often been visited as a natural curiosity, and is considered by tourists one of the lions of the State. To be appreciated in its full beauty, it should be approached from the Ocklewaha. For more than a week I had been tediously ascending this river in a pole-barge, wearied with the monotony of the dank and gloomy forests that everywhere shade its inky stream,[341] when one bright morning a sharp turn brought us into the pellucid waters of the Silver Spring Run. A few vigorous strokes and we had left behind us the cypress swamps and emerged into broad, level savannas, that stretched miles away on either hand to the far-off pine woods that, like a frame, shut in the scene. In the summer season these prairies, clothed in the luxuriance of a tropical vegetation, gorgeously decked with innumerable flowers, and alive with countless birds and insects of brilliant hues, offer a spectacle that once seen can never be forgotten.
But far more strangely beautiful than the scenery around is that beneath—the subaqueous landscape. At times the bottom is clothed in dark-green sedge waving its long tresses to and fro in the current, now we pass over a sunken log draperied in delicate aquatic moss thick as ivy, again the scene changes and a bottom of greyish sand throws in bright relief concentric arcs of brilliantly white fragments of shells deposited on the lower side of ripple marks in a circular basin. Far below us, though apparently close at hand, enormous trout dash upon their prey or patiently lie in wait undisturbed by the splash of the poles and the shouts of the negroes, huge cat-fish rest sluggishly on the mud, and here and there, every protuberance and bony ridge distinctly visible, the dark form of an alligator is distended on the bottom or slowly paddles up the stream. Thus for ten miles of an almost straight course, east and west, is the voyager continually surprised with fresh beauties and unimagined novelties.
The width of the stream varies from sixty to one hundred and twenty-five feet, its average greatest depth about twenty, the current always quite rapid. For about one mile below its head, forests of cypress, maple, ash, gum, and palmetto adorn the banks with a pleasing variety of foliage. The basin itself is somewhat elliptical in form, the exit being at the middle of one side; its transverse diameter measures about one hundred and fifty yards, (N. E., S. W.,) its conjugate one hundred yards. Easterly it is bordered by a cypress swamp, while the opposite bank is hidden by a dense, wet hammock. A few yards from the brink opposite the exit runs a limestone ridge of moderate elevation covered with pine and jack-oak.
The principal entrance of the water is at the northeastern extremity. Here a subaqueous limestone bluff presents three craggy ledges, between the undermost of which and the base is an orifice, about fifteen feet in length by five in height, whence the water gushes with great violence. Another and smaller entrance is at the opposite extremity. The maximum depth was at the time of my visit forty-one feet. The water is tasteless, presents no signs of mineral matter in solution, and so perfectly diaphanous that the smallest shell is entirely visible on the bottom of the deepest portion. Slowly drifting in a canoe over the precipice I could not restrain an involuntary start of terror, so difficult was it, from the transparency of the supporting medium for the mind to appreciate its existence. When the sunbeams fall full upon the water, by a familiar optical delusion, it seems to a spectator on the bank that the bottom and sides of the basin are elevated, and over the whole, over the frowning crags, the snow-white shells, the long sedge, and the moving aquatic tribes, the decomposed light flings its rainbow hues, and all things float in a sea of colors, magnificent and impressive beyond description. What wonder that the untaught children of nature spread the fame of this marvellous fountain to far distant climes, and under the stereoscopic power of time and distance came to regard it as the life-giving stream, whose magic waters washed away the calamities of age and the pains of disease, round whose fortunate shores youths and maidens ever sported, eternally young and eternally joyous!
During my stay I took great pains to ascertain the exact temperature of the water and from a number of observations made at various hours of the day obtained a constant result of 73.2°, Fahrenheit. This is higher than the mean annual temperature of the locality, which, as determined by a thermometrical record kept at Fort King near Ocala for six years, is 70.00°; while it is lower than that of the small mineral springs so abundant throughout the peninsula, which I rarely found less than 75°. It is probable, however, that this is not a fixed temperature but varies with the amount of water thrown out. Competent observers, resident on the spot, informed me that a variation of three feet in the vertical depth of the basin had been known to occur in one year, though this was far greater than usual. The time of highest water is shortly after the rainy season, about the month of September, a fact that indicates the cause of the change.
Visiting the spring when at a medium height I enjoyed peculiar advantages for calculating the amount of water given forth. The method I used was the convenient and sufficiently accurate one of the log and line, the former of three inches radius, the latter one hundred and two feet in length. In estimating the size of the bed I chose a point about a quarter of a mile from the basin. The results were calculated according to the formulæ of Buat. After making all possible allowance for friction, for imperfection of instruments, and inaccuracy of observation, the average daily quantity of water thrown out by this single spring reaches the enormous amount of more than three hundred million gallons!
Numbers such as this are beyond the grasp of the human intellect, bewildering rather than enlightening the mind. Let us take another unit and compare it with the most stupendous hydrographical works of man that have been the wonders of the world. Most renowned of these are the aqueducts of Rome. In the latter half of the first century, when Frontinus was inspector, the public register indicated a daily supply of fourteen thousand and eighteen quinaria, about one hundred and ninety-six million gallons. Or we can choose modern instances. The city of London is said to require forty million gallons every twenty-four hours, New York about one-third, and Philadelphia one-quarter as much. Thus we see that this one fount furnishes more than enough water to have satisfied the wants of Rome in her most imperial days, to supply plenteously eight cities as large as London, a score of New Yorks, or thirty Philadelphias. By the side of its stream the far-famed aqueduct of Lyons, yielding one million two hundred and nine thousand six hundred gallons daily, or the Croton aqueduct, whose maximum diurnal capacity is sixty million gallons, seems of feeble importance, while the stateliest canals of Solomon, Theodoric, or the Ptolemies dwindle to insignificant rivulets.
Neither is this the emergence of a sunken river as is the case with the Wakulla fountain, but is a spring in the strictest sense of the word, deriving its sustenance from the rains that percolate the porous tertiary limestone that forms the central ridge of the peninsula.