March 29, 1894] 



NA TURE 



515 



he had exhumed bore traces of having been gnawed ; and later 

 •on Adams made similar observations. 



Notwithstandinij, however, the most diligent research ex- 

 tending over a period of twenty years, no further evidences of 

 the presence of carnivoras were forthcoming. These were the 

 first remains met with. 



Equally interesting was the discovery which was made in 

 Trench v. Among the remains which were exhumed Mr. 

 Arthitr Smith Woodward has determined the third metacarpal 

 of man. It was found at a depth of 3 ft. 6 in. from the surface, 

 and underlying a layer containing pottery. It is probably of 

 great antiquity, having been extracted from one of the earliest 

 layers in the cavern. 



That these deposits are of great antiquity there can be no 

 doubt. The state of mineralisation in which the bones were 

 found was most complete ; and when, in addition to this, the 

 height of forty feet above the gorge bed at which the cavern is 

 at present situated be considered, in conjunction with the ex- 

 tremely slow and gradual character of the processes of erosion 

 which were engaged in cutting down the bed of the gorge to 

 its present level— when these, and the other equally important 

 points regarding the great changes in climate that have taken 

 place between this and then be duly weighed, the author thinks 

 that he would be justified in referring the Har Dalam deposits to 

 a considerably remote epoch. 



Such then in brief are a few of the evidences bearing on the 

 prehistoric history of the Maltese Islands which these excavations 

 have supplied us with — evidences which have added one more 

 arch to the bridge with which the geologist and the archaeologist 

 in the Maltese Islands are endeavouring to span the gulf which 

 at present divides their labours. 



GEOGRA PHY IN CA UCA S US. 

 A RECENT volume of the Memoirs (Zapiski) of the Caucasian 

 "^ Branch of the Russian Geographical Society (vol. xv. ) is 

 of more than usual interest. It opens with a paper, by Mr. 

 Konshin, on the old beds of the Amu-daria, accompanied by a 

 map which shows the consecutive decrease of the area of the 

 Caspian sea since the beginning of the Post-Pliocene epoch. 

 It is known that the Russian geologist was first to point out 

 that what had been previously described as old beds of the 

 Amu are not beds at all, but elongated channels occupied 

 once by the salt waters of the Caspian. The writers of anti- 

 quity were not wrong in representing the Caspian sea as a 

 basin, elongated from west to east, and in ignoring the exist- 

 ence of Lake Aral as a lake separated from the Caspian. At 

 the beginning of the Post-Pliocene epoch, and perhaps later on 

 as well, the Caspian sent eastward two wide gulfs, one of which 

 reached the longitude of Merv, and covered what is now a 

 depression in the south of the Kara-kum elevated plain ; while 

 another gulf, stretching north-eastwards, included Lake Aral 

 and what is now the delta of the Amu, as far as Khiva and 

 Pitnyak. Thus, it was not the Amu which reached the Caspian, 

 but the sea which reached the river by e.ttending much further 

 eastward than it does now. The Chink, which has so often been 

 described as an old bed of the Amu, was the northern coast of the 

 Kara-kum gulf ; while the river-like beds of the Sary-kamysh de- 

 pression were narrow channels through which the waters of Lake 

 Aral occasionally found their way into the Caspian, long time 

 after the two great lakes had been separated from each other. Mr. 

 Konshin's little map very well illustrates the subsequent changes 

 of the form of the Caspian. It may only be added that an ex- 

 ploration of the Ust-urt, and especially of the chain of lakes 

 which crosses it from west to east- — connecting, so to say, the 

 Caspian with Lake Aral — is extremely desirable ; it seems very 

 probable that another channel of communication between the 

 two great lakes will be discovered in that direction as well. 

 A. V. Pastukhoff's communication about his ascension on the 

 Elbrus and the Khalatsa peak, in July, 1890, is also full of in- 

 terest, and is accompanied by excellent photographs and a map. 

 On the top of this latter peak, which reaches 11,915 feet, the 

 party was overtaken by a snowstorm, during which they were 

 surrounded by a most beautiful display of electric fires ; all 

 their fur coats, their hair, their moustaches, as well as the poles 

 of their tents and all metallic things, were enveloped in luminous 

 discharges, which came to an end only after a discharge of 

 thunder. The thunderstorm was terrible, especially one dis- 

 charge of globular thunder, which rendered all the party 

 fienseless for a time. 



NO. 1274, VOL. 49] 



Dr. Dinnik's descriptions of his journey in Western Ossetia, 

 as well as in Pshavia and Khevsuria, are full of valuable obser- 

 vations, especially as regards glaciers and traces of an extensive 

 previous glaciation of the main chain. And Mr. FilipofTs 

 remarks relative to the present changes of level in the Caspian, 

 show that the level of the sea is continually oscillating in its dif- 

 ferent parts, and never remains quite horizontal ; it depends 

 very much upon the different winds. 



Mr. N. Alboff's reports of his botanical explorations in 

 Abhasia and Lazistan are most valuable, the more so as his 

 conclusions relative to the flora of West Caucasus, very dif- 

 ferent from those arrived at by MM, Krasnoff and Kuznetsoff, are 

 based on most elaborate studies and extensive collections. 



Another important paper is contributed to the same volume 

 by K. N. Rossikoff, on the desiccation of lakes on the northern 

 slope of Caucasus. These lakes belong to three diff'erent cate- 

 gories. Those on the coasts of both the Caspian sea and the 

 sea of Azov have originated from old lagunse, or in the deltas 

 of the rivers. They attain but a small depth (3^ fathoms is 

 the maximum depth observed), and many of them are brackish. 

 The lakes of the Steppe-region occupy distinct depressions of 

 the surface, and are fed by little temporary streams and under- 

 ground water. And, finally, there is a small number of lakes 

 at the footings of the Main Ridge and in the mountain region 

 itself. Now, all the lakes relative to which there are reliable 

 observations made during the years 1881 to 1891, are decidedly 

 in a period of desiccation. Most of the lakes of the Steppe- 

 region have either entirely disappeared, or are living the last 

 years of their existence ; they will exist no more in a few years. 

 The lakes scattered at the foot of the mountains are also in 

 decrease ; their levels have sunk during the last eight years of 

 the above period by an average of ninety inches. As to the 

 lakes of the mountain region, their desiccation seems chiefly to 

 depend upon the destruction of forests. These facts entirely 

 confirm the widely-spread belief that the climate of Caucasus is 

 becoming more and more dry during the last forty or fifty years. 



The volume is concluded with an extensive paper by Dr. 

 Pantyukhoff', full of most valuable anthropological measurements 

 of representatives of the various nationalities and tribes of 

 Caucasus, and accompanied by many engravings. 



ISOPERIMETRICAL PROBLEMS? 



Dido, B.C. 800 or 900. 

 Horatius Codes, B.C. 508. 

 Pappus, Bjok V. A.D. 390. 

 John Bernoulli, a.d. 1700. 

 Euler, A.U. 1744. 



Maupertuis (Least Action), b. 1698, d. 1759. 

 Lagrange (Calculus of \'ariations), 1759. 



Hamilton (Actional Equations of Dynamics), 1S34. 

 Jjiouville, 1840 to i85o. 



THE first isoperimetrical problem known in history was prac- 

 tically solved by Dido, a clever Phoenician princess, who 

 left her Tyrian home and emigrated to North Africa, with all 

 her property and a large retinue, because her brother Pygmalion 

 murdered her rich uncle and husband Acerbas, and plotted to 

 defraud her of the money which he left. On landing in a bay 

 about the middle of the north coast of Africa she obtained a 

 grant from Hiarbas, the native chief of the district,, of as much 

 land as she could enclose with an ox-hide. She cut the ox-hide 

 into an exceedingly long strip, and succeeded in enclosing 

 between it and the sea a very valuable territory^ on which she 

 built Carthage. 



The next isoperimetrical problem on record was three or four 

 hundred years later, when Horatius Codes, after saving his 

 country by defending the bridge until it was destroyed by the 

 Romans behind him, saved his own life and got back into 

 Rome by swimming the Tiber under the broken bridge, and 

 was rewarded by his grateful countrymen with a grant of as much 

 land as he could plough round in a day. 



In Dido's problem the greatest value of land was to be en- 

 closed by a line of given length. If the land is all of equal 

 value the general solution of the problem shows that her line 

 of ox-hide should be laid down in a circle. It shows also that 

 if the sea is to be part of the boundary, starting, let us say, south- 



lA lecture delivered at the Royal Institution, May 12, 1893, by Lord 

 Kelvin, Pres. R.S. . , . , ^. • r 



-Called Byrsa, from ^vpffa, the hide of a bull. (Smith s Dictionary ot 

 Greek and Roman Biography and Mythology," article "Dido.") 



