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THE POPULAR SCIENCE MONTHLY, 



from the extremity of the shott El-Djerid, to 

 form the proposed sea. In a letter from 

 M. Roudaire to M. de Lesseps, the advan- 

 tages which may be expected to result from 

 the creation of this new sea are stated to 

 be " an immense amelioration of the climate 

 of Algeria and Tunis, since the moisture 

 caused by the evaporation from the vast ex- 

 panse of water will be driven by the prevail- 

 ing southerly winds over these countries, 

 forming a layer of humid atmosphere which 

 will greatly mitigate the intensity of the so- 

 lar rays and retard the cooling of the earth 

 by radiation during the night. The proposed 

 sea, too, being navigable for ships of the 

 greatest draught, will also open a new com- 

 mercial route for the districts lying to the 

 south of the Aures and the Atlas range ; while 

 watercourses which from the south, west, 

 and north converge toward the shotts, but 

 which are now dry during the greater part 

 of the year, will again become rivers, as they 

 once undoubtedly were, leading ultimately 

 to the fertilization of vast tracts of now 

 desert land on their banks." 



On the Antiqaity of Man. — Starting from 

 the opinion generally accepted among geolo- 

 gists, that man was on the earth at the close 

 of the Glacial epoch, Professor B. F. Mudge 

 adduces evidence to prove that the antiquity 

 of man can not be less than 200,000 years. 

 His argument, as given in the " Kansas 

 City Review of Science," is about as fol- 

 lows : After the Glacial epoch geologists fix 

 three distinct epochs, namely the Champlain, 

 the Terrace, and the Delta, all supposed 

 to be of nearly equal length. Now, we have 

 in the Delta of the Mississippi a means of 

 measuring the duration of the third of these 

 epochs. For a distance of about two hun- 

 dred miles of this delta are seen forest- 

 growths of large trees, one over the other, 

 with interspaces of sand. There are ten 

 of these distinct forest-growths, which have 

 begun and ended one after the other. The 

 trees are the bald cypress {Taxodium) of 

 the Southern States, and some of them were 

 over twenty-five feet in diameter. One con- 

 tained over 5,Y00 annual rings. In some 

 instances these huge trees have grown over 

 the stumps of others equally large; and 

 such instances occur in all, or nearly all, of 

 the ten forest-beds. This gives to each 



forest a period of 10,000 years. Ten such 

 periods give 100,000 years, to say nothing 

 of the time covered by the interval between 

 the ending of one forest and the beginning 

 of another — an interval which in most casts 

 was considerable. " Such evidence," writes 

 Professor Mudge, " would be received in any 

 court of law as sound and satisfactory. We 

 do not see how such proof is to be discarded 

 when applied to the antiquity of our race. 

 There is satisfactory evidence that man lived 

 in the Champlain epoch. But the Terrace 

 epoch, or the greater part of it, intervenes 

 between the Champlain and the Delta epochs, 

 thus adding to my 100,000 years. If only 

 as much time is given to both those epochs 

 as to the Delta period, 200,000 years is the 

 total result." 



Tbe Immensity of tlic Stars. — We take 

 from " Le Monde de la Science " the fol- 

 lowing interesting " Considerations on the 

 Stars," by Professor J. Vinot : " It is known 

 that the stars are true suns, that some of 

 them are larger than our own sun, and that 

 around these enormous centers of heat and 

 light revolve planets on which life certainly 

 exists. Our sun is distant from us 38,000,- 

 000 leagues, but these stars are distant at 

 least 500,000 times as far — a distance that 

 in fact is incommensurable and unimagi- 

 nable for us. Viewed with the unaided eye 

 the stars and the planets look alike, that is, 

 appear to have the same diameter. But, 

 viewed through the telescope, while the 

 planets are seen to possess clearly appreci- 

 able diameters, the stars are still only mere 

 luminous poiuts. The most powerful of 

 existing telescopes, that of Melbourne, which 

 magnifies 8,000 times, gives us an image of 

 one of our planets possessing an apparent 

 diameter of several degrees. Jupiter, for 

 instance, which, seen with the naked eye, 

 appears as a star of the first magnitude, 

 with a diameter of 45" at the most, will in 

 this telescope have its diameter multiplied 

 8,000 times, and will be seen as if it occu- 

 pied in the heavens an angle of 100°. Mean- 

 while a star alongside of Jupiter, and which 

 to the eye is as bright as that planet, will 

 still be a simple dimensionless point. Never- 

 theless that star is thousands of times more 

 voluminous than the planet! Divide the 

 distance between us and a planet by 8,000, 



