178 



♦ KNOW^LEDGE 



[June 1, 1888. 



tlie Oeningen Lake. Tapirs, mastodons, rhinoceros, musk 

 deer, apes, opossums, three-toed horses, were among the in- 

 habitants of that Alpine region. Ancient ruminants long 

 since extinct were numerous. The huge dinotherium floated 

 on the lake, or held on to the banks by the huge tusks of 

 his under-jaw. Frogs, toads, lizards, snakes, squirrels, hares, 

 beavers, were abundant, as well as numbers of small carni- 

 vores to feed upon them ; for if Nature " never makes 

 mouths but she finds food," she assuredly attends to the 

 converse arrangement with at least equal anxiety. 



The last stage of all — that is, the last of all the grander 

 stages of geologic time — belongs to the glacial era. As far 

 as Lyons along the Rhone valley, extending through the 

 transverse valleys of the Jura as far as Ornans (near 

 Besancjon), along the Rhine valley above Basle, over the 

 Black Forest, and down the valley of the Danube beyond 

 Sigmaringen eastwards (joining the glaciers from the 

 Bavarian Alps) as far as Munich, far out into the plains 

 of Lombardy on the south, the moraines of the mighty 

 Alpine glaciers of the Pleistocene age can be recognised. 

 In some places the moraine rests on marine Pliocene beds ; 

 and there are reasons for believing that In several directions 

 the glaciers reached the sea, as those of Greenland do now. 

 The Great Ice Age, whose stupendous records thus remain, 

 was not continuous. In interglacial periods the ice retreated, 

 and allowed an abundant vegetation to flourish, even in the 

 heart of Switzerland. The strata belonging to these milder 

 periods overlie the moraines of more ancient glaciers, inter- 

 stratified with sands and river gravels, and are in turn sur- 

 mounted by erratic boulders, the product of a later glacial 

 era. 



With these Pleistocene pages, bringing the history down 

 to within perhaps a hundred thousand years of our own 

 time, our study of the Alpine record may well cease. It is 

 but one set of books, one set out of many of like nature, 

 some promising to be more striking still in their teaching 

 when they have been fully studied. Other mountain ranges 

 speak of still more stupendous processes of formation, and 

 even of vaster time-intervals. Others, less massive, speak 

 nevertheless of a more venerable age, since they have now 

 gone far upon their road to decay. Others, although they 

 have become mere wrecks, are yet more interesting as being 

 the earth's most venerable antiques. 



The hills are indeed " everlasting," viewed as men must 

 view them. Even as the stellai' regions are for us practically 

 infinite, so do the records of the earth run over periods 

 which are for us practically eternal. Yet in another and 

 a grander sense the everlasting hills are evanescent. 



They flow 

 From form to form, and nothing stands ; 

 Like mists they melt, the solid lands — 

 Like clouds they slia|ie themselves and go. 



Geological AHCaiTBCTURB. — A curious effect of the wear and 

 tear to which the earth's crust is ever being subjected is exhibited 

 in the singularly capped pinnacles e.tisting on the South River in 

 the Wahsatch Mountains. There are hundreds of these slender 

 pillars, ranging in height from forty to 400 feet, most of them 

 crowned by large caps of stone. Tliey are not works of human art, 

 as might almost be imagined, but are the memorial monuments of 

 the once rounded hills, from which they have been cut by the action 

 of air and water. These pinnacles alone remain of some square 

 miles of solid rock, which has been washed away to a depth of 

 too feet. The greater hardness of the surface has caused it to 

 resist corrosion more than the underlying rock, thus leaving the 

 huge stone caps perched high in air on the points of the thin 

 columns. At one point, while this carving process has been going 

 on, a thin wall of rock was penetrated, leaving a lofty natural 

 bridge or arch, which adds to the picturesqueness of a remarkable 

 landscape. 



DEPENDING 



SIMPLE MECHANICAL TRICKS 

 ON GRAVITY. 



MONG mechanical tricks few are 

 effective than those depending on 



more 

 ravily, 

 and few are more readily managed, the 

 constructions required for such tricks being 

 usually very simi)le. They are also highly 

 instructive and suggestive. It is indeed 

 easy for the young mechanician, as soon as 

 he has caught the principle on which they depend, to 

 devise new tricks, not less striking than those more 

 familiarly known. 



In the first place it should be noted that in most of the 

 mechanical tricks depending on gravity the observer is to 

 some degree deluded ; for the selfsame principle of gravity 

 may be illustrated in such a way that the experiment 

 seems natural and ordinary, or in another which makes it 

 appear surprising and even startling. 



Take, for instance, the experiment of suspending a weight 

 on a coin standing on edge upon the point of a needle. This is 

 illustrated sufliciently in fig. 1. Two knives K and K' are 

 thrust into a cork C, into the under side of which, as shown 

 in the figure, a coin, ss' (a shilling is the most convenient) 

 is thrust. When this combination is placed in the manner 



Fig. 1. 



Fig. 2. 



shown, so that the under edge of the coin rests on the point 

 of a needle n, fixed vertically in any way (as by thrusting it 

 through a cork in the mouth of bottle B B'), the apparently 

 unstable poising is found to be in reality perfectly stable. 

 The knives can be struck so as either to .set the balanced 

 combination oscillating or to set it rotating upon the needle's 

 point, without any risk of the balance being destroyed. 



Though this experiment or trick has a surprising ap- 

 pearance, the principle on which it depends may be illus- 

 trated in practically the same way without causing any 

 surprise whatever ; and though this is not the thing 

 specially aimed at in mechanical tricks, yet it is instructive 

 to see how a trick which seems surprising when perfoi'med 

 in a particular way resolves itself into a quite ordinary 

 experiment when difi'erently arranged. 



This may be done ibr the trick we have considered by 

 means of such an arrangement as is shown in fig. 2. Here a 

 needle or other .sharp-pointed support is fixed vei'tically 

 into a bar A B, and on the point of this a wire beaiing two 

 weights W and W', and attached in the manner shown to 

 a disc D (which may be a shilling if preferred), is set 

 simjjly hanging upon the needle's point. In this experi- 

 ment it is so obvious that the case is merely one of suspen- 

 sion, the equilibrium being akin to the swinging of the 

 pendulum, that the experiment has scarcely even any 

 interest for the observer : he sees at once that the wired 

 weights ouf/hl to hang freely and .safely on the needle's 

 point. But it is obvious that if we remove the part of the 

 wire under the weights, and replace the parts D W and 

 D W by straight wires we have reproduced — without alter- 



