APPLETONS' POPULAR SCIENCE MONTHLY. MAY, 1896. NIAGARA AS A TIMEPIECE. By J. W. SPENCER, A. M., Pп. D., F. G. S. IAGARA FALLS IN HISTORY.-Guided by an Indian chief, La Salle and Hennepin visited Niagara Falls in 1678, but it was not until 1697 that Hennepin published his picture of the cataracts, which, in spite of the rude perspective of two centuries ago and the prominence of the voyageurs, is famous for having been the first pictorial representation of the falls of Niagara (Fig. 1). The existence of the falls was known a century and a half earlier than Hennepin's narrative through reports of the Indians to Jacques Cartier (1535). In the early part of the seventeenth century, Champlain and several Jesuit fathers mention the cataract, which was mapped by two of them under the name of "Onigara." Reproductions of Hennepin's picture were frequently made, but there appear to be no fairly good drawings of the falls preserved older than that of Lieutenant William Pierie, of date of 1768 (Fig. 2). The scenery and even the geology of the Niagara district have been known for nearly half a century, and hundreds and perhaps thousands of papers have been published upon the falls of Niagara. Yet "problems settled in a rough and ready way by rude men absorbed in action demand renewed attention and show themselves to be unread riddles . . . when men have time to think." Even now it is scarcely fifteen years since the history of the falls began to be known. ... If we look at a picture of the Falls of Montmorency, near Quebec (Fig. 3), cascading about two hundred and seventy-five feet over the wall of the St. Lawrence almost directly into the river VOL. XLIX.-1 itself, without flowing through any cañon whatever, and then glance at the gorge of Niagara River, seven miles long, of which only a fragment can be seen in a picture (Fig. 4), the striking difference awakens inquiry. The cause does not lie in either the magnitude of the streams or in the character of the rocks; it is a question of the difference of the age, for Niagara Falls once cascaded from the edge of the mountain wall (Fig. 16) directly into the expanded waters of the Ontario basin just as the Montmorency stream is pouring into the St. Lawrence River to-day. EARLY ESTIMATES OF THE AGE OF NIAGARA FALLS.-All attempts at reducing geological time to solar years meet with great difficulties, yet Niagara Falls have been used as a chronometer as FIG. 1.-FACSIMILE OF A VIEW OF NIAGARA FALLS BY FATHER HENNEPIN. frequently as any other natural phenomenon, and indeed Niagara is perhaps the best measurer that we have. Even at an early date, when the antiquity of the earth was not a popular doctrine, Andrew Ellicott (in 1790) divided the length of the gorge by the supposed rate of recession of the falls, and assigned fifty-five thousand years as the age of the cataract. Forty years later Bakewell reduced the time to twelve thousand years, and a few years afterward Lyell's estimate of thirty-six thousand years became popular and remained so until about fifteen years ago. This method of dividing the length of the chasm by the rate of recession was correct as far as it went, but even the rate was not then known. METHOD OF COMPUTING THE AGE OF THE FALLS.-Many years FIG. 2.-CATARACT OF NIAGARA FALLS, WITH THE ADJACENT COUNTRY. (From a drawing on the spot by Lieutenant William Pierie, of the British Artillery, 1768.) This picture was kindly furnished by Peter A. Porter, Esq., of Niagara Falls. ago Prof. James Hall laid the foundation of all future calculations when he made the first instrumental survey of the crest of the falls. The changes in the crest have been measured three times since, and from these surveys the mean recession for nearly half a century is now known and has been found to be much more rapid than was formerly supposed. If the whole history of the falls of Niagara were thus told, then it would appear that their age is about nine thousand or ten thousand years. Indeed, some writers, among others Mr. Gilbert, took this reduced estimate and minimized it to seven thousand years, not knowing or overlooking the history of the river which tells of the changing conditions; but these views he now abandons. The chronometer needed correction. During a term of several years of actual work, but extended through a decade and a half, for the investigations were often blocked with difficulties, the writer has been able to decipher |