171 



KNOWLEDGE. 



[August, 1903. 



teetli are iu course of elimination, while the large pair 

 represent the tusks of the mastocluns, ■which are thus shown 

 to correspond to the second of the three typical pairs oE 

 incisors. In the lower jaw the canines and the third pair 

 of incisors have disappeared ; while of the two remaining 

 pairs, the first are small and functionless, but the second 

 are large and project forwards in a manner recalling the 

 lower tusks of the mastodons, of which they are the 

 forerunners. 



Although it would be out of place to discuss its probos- 

 cidean features here, it mav be mentioned that this skull 

 lacks the great elevation characteristic of the elephants, 

 but has the brain-cavity relatively large. In the former 

 respect there is an almost complete gradation from the 

 elephants through the mastodons to the mceritherium. 

 Obviously the latter animal must have been very short- 

 lived in comparison with an elephant ; and it is also 

 evident that it was either trunkless or furnished with a 

 rudiment of proboscis. 



The limb-bones are not yet fully described, but it is 

 suggested that they resemliled those of the extinct American 

 unitatherium in being pdaced vertical ly one above another. 

 If this be so, the theory that elejahants acquired their 

 straight limbs in order to support their great weight will 

 certainly not hold good. 



The discovery of these new forms has shown that 

 elephants and mastodons, in place of forming a group of 

 unknown origin, are the descendants of small, short-lived 

 and trunkless animals, with a type of dentition not very 

 far removed from that characteristic of hoofed mammals 

 in general. And it is further evident that elephants, in 

 place of being primitive, are a very highly specialised type. 

 Moreover, the absence of remains of forerunners of the 

 mastodons from the Tertiary formations of Europe and 

 Asia, affords evidence that the evolution of the mastodons 

 took place in Africa. 



MURRAY AND CHRYSTAL ON "SEICHES." 



By Dr. J. G. McPherson, f.b.s.e. 



The other evening two very interesting papers were read 

 to the Royal Society of Edinburgh on " Seiches," or 

 "standing waves," by Sir John Muri-ay and Prof. Chrystal, 

 the former on the observations and the latter on the theory. 



Besides the ordinary forms of waves in fresh-water lakes 

 there are standing waves which have only recently been 

 carefully observed and studied. It is curious to notice 

 that though there is no longitudinal or transverse dis- 

 placement, there is an oscillatory movement of the whole 

 body of water, so that when at one end of the lake the 

 water is raised by a wave of several inches there is a 

 corresponding depression of the water at the other end. 



Forrel, the distinguished authority on waves and their 

 motion, noticed the phenomena in the Lake of (jleneva. but 

 he could not accurately account for these. These " seiches," 

 as the standing or undisplaced waves of the entire mass 

 of water are now called, have been recently observed in 

 Como and other Continental lakes; and Prof. Henry has 

 observed a raising of Lake Erie in America to the extent of 

 eight' feet, quite independent of the waves caused bv strong 

 winds. Sir John Murray and his assistants. Dr. Johnston 

 and Messrs. Murray and Garrett, during last summer, when 

 engaged in bathymetrical observations in Scottish fresh- 

 water lochs, noticed some curious wave phenomena, but 

 their instruments were not sufficiently accurate to produce 

 satisfactory results. However, they have now secured 

 the excellent instrument made in Geneva, which has also 

 been ordered from different stations in Japan and America, 

 and they hope this summer to make more accurate observa- 



tions, so as to afford Prof. Chrystal sufficient correct 

 data for mathematical investigation. 



Mr. E. Mailagan Wedderbum illustrated the different 

 forms of standing waves by an ingenious apparatus ; of 

 course the depth of the water in the rectangular trough 

 was far deeper iu proportion to the length of the trough 

 than is found in natm-al lakes ; but it brought out to the 

 eye the principles of the motions. In one case the wave 

 of the mass had only one node in the centre, where the 

 bottom of the trough was level. While the water was in 

 motion on both sides of the node, the one part raised, the 

 other part depressed at the same moment, the water at 

 the node was perfectly still. By another arrangement of 

 difference of level iu the base, Mr. Wccldfrbin-n managed 

 to produce wave motion with two nodes where the water 

 at two points on the surface was still, and the waves 

 were plainly seen in the three remaining portions. By 

 continuing the arrangement he produced several nodes. 

 Thus seiches are uninodal, binodal, and plurinodal, 

 according to the structure of the base of the lakes. They 



(a) represents a uninodal wave, the dotted part being tlie 

 complement. 



(A) represents a binodal wave, the dotted part being the 

 complement. 



are rhythmical, and similar to the nodal points of sound- 

 waves. By an ingenious adjustment of the apparatus, 

 Mr. Wedderburn was able to produce a uninodal wave 

 and a plurinodal wave by two sets of motions at the same 

 instant, and a most curious result was produced. Again, 

 by making certain alterations in the base, the nodes were 

 made to occur nearer one end of the trough than the other. 



Attacking the general solution by Bessel's fonnula, 

 Du Boy's period (as guessed by Newton), Kelland's 

 formula, Laplace and Merian's formulae. Prof. Chrystal 

 has come to some, so far, satisfactory theoretical results ; 

 but he is waiting for physical observations of the seiches 

 in the lakes liefore he goes further, as it would be a mere 

 waste of time so far as any practical and useful results 

 could be obtained. 



Prof. Chrystal made some beautiful pendulum experi- 

 ments to illustrate the oscillatory changes caused by a sort 

 of physical sympathy. From this he concluded that 

 though the surface of Lake Erie is often troubled by 

 seiche motion to a height of eight feet, deep down the 

 water is motionless. The matter is still in its infancy, 

 but this note will indicate the lines on which these 

 observers and calculators are proceeding. 



WIRELESS TELEGRAPHY AND WEATHER 

 FORECASTING. 



By Arthue H. Bell. 



Wireless telegraphy is doubtless destined to play an 

 important part in furthering the advancement of many 

 projects connected with the life of the nation ; but it may 



